MB100 development [Archive] - Kiwi Biker forums

Hilleye

27th September 2011, 20:42

Just getting back into bucket racing.

Had the MB100 dynotuned in prepartion for the Battle of the Buckets at Ruapuna on 15 Oct 11. Results (shown below) were mixed.

247520.

Positives from the session on the dyno were:
1. The bike is no longer in grave danger of seizing because it was running way, way, too lean.
2. I actually know where its making power and can now ride it accordingly.

Negatives:
1. Bike is making less power than expected and is quite peaky. Peak power is also being made quite low at around 9200rpm. Exhaust seems to be the culprit on this.
2. Carb seems to be too large for the bike. Diagnosed from:
No power increase with a jetting increase.
Jetting also can't be increased as carb won't flow enough air. Raising the needle to flow more air (to allow bigger jet) just causes bogging issues.
Unable to reduce the jetting size without compromising the fuel/air ratio and placing the engine at risk

What I don't have is an objective point of view of what can reasonably be expected from this motor and where I should start to try and improve it. I've heard figures of upto 30hp being bandied around, but would be happy with a little more than what I'm getting over a much broader rev range.

Bike is running a Mikuni carb that's been machined out to 27mm and what looks like a home made exhaust system with a can of unknown origin.

Gigglebutton

27th September 2011, 20:52

koba

27th September 2011, 21:13

OK, from reading that quickly It looks as though you may have a few miss-understandings about some fundamental concepts in engine tuning.

I suggest if you want to get ever reasonably serious about it you should read the ESE works tuner thread, In there are heaps of links and information. Especially valuable are the links to books by A. Graham Bell and Gordon Jennings.

They won't tell you everything you need to know but they are a good start and the thread should help heaps with your understanding of different aspects of engine tuning.

speedpro

27th September 2011, 21:19

MB100s are REALLY good engines. You don't mention porting. The transfers can be left alone initially. It's hard to describe but you want to increase the exhaust port area above the level of the transfer ports. On the intake try and find a 4-petal Yamaha reed block and rubber carb mount. With a bit of filing and an extra pair of holes just above the bottom pair they bolt on quite tidily. The single piston-controlled intake port needs an extra port added each side though you can get good results just filling in the intake so flow is directed through a slightly enlarged single port. 28mm is a good carb size and a better carb would be a later model keihin. If you go for a bit of compression you will want to change the ignition system. Aim for about 13 to 15:1 depending on fuel you use. A good pipe is essential. An MB engine should rev to 13,000rpm with no worries and run to over 14,000rpm when needed.

A few things you've said are a bit hard to understand. Be very careful when tuning the motor on a bigger track if you are unsure of how it all works. It's real easy to put a hole in a piston. You should expect 20+hp without too many worries. Pete Sales at Total Motorcycles near Palmerston North does a very nice basic port setup for reasonable money. He could spin the head as well for a nice combustion chamber.
Try and score a MB50 6-speed gearbox, they drop straight in and are worth tracking down.

koba

27th September 2011, 21:31

Everyone is going to have an Idea on it but BEWARE some ideas will be given to you from people who are themselves confident they are knowledgeable but in fact are a wee bit less informed than they realise. (Speedpro Isn't one of those).

Having said that I will add my opinion which Isn't the most authoritive - by far.

I have an MB100 that is almost standard but I've done a few things to, I would look into the reed block before the carb, although you could probably go up from 27 mll to about 20 - 32 for a rouandslide or 28-30 for a flatslide. Bigger is OK later, but that seems about ballpark for a lower tune motor.

The reed block.

Common mod is to use an RD350 reedblock and manifold, it had 4 petals and is alot bigger, It also has a lift profile that isn't as severe, as the MB one. Should be able to find these bits for cheap or free as they are often discarded from RD's in favour of RZ units.
I saw a large gain in performance when I was still running the completely standard engine with just a pipe when I changed to fibre reeds, I don't know the dyno figures but it added considerably more usable rev range up top. (Cheers to F5 Dave for that advice)
The bend on the standard stops is real severe and Speedpro mentioned they could be re-bent to give the same sort of lift with a less severe bend. Look at other more performance based reed blocks to get an idea. The holes need to be slotted or re-drilled to allow that.

The pipe.
Pipe is all important.
It is important it matches the engine.
My pipe is close to the ESE 18hp build, It works OK on a kart track on standard porting but if you are running at Ruapuna you may need more outright power. You want to start by measuring the pipe you have. A bit of string and/or flexible wire will help.

Hopefully that adds positively to the pile of advice you are likely to get.

Above all remember to think, learn, take notes, change one thing at a time, Think some more, read, learn, think, read, think, learn...etc

koba

27th September 2011, 21:34

Speedpro is on the money.

Now I look at the graph...

That isn't that bad really as a start point, I'm racing OK with less than that now. (Kart track though)

EDIT: Ah, Nope, now I see, was looking at the figures on the wrong side, 14 is a bit sadder than 17. I think mine has about 14.

bucketracer

27th September 2011, 21:59

What I don't have is an objective point of view of what can reasonably be expected from this motor and where I should start to try and improve it. I've heard figures of upto 30hp being bandied around, but would be happy with a little more than what I'm getting over a much broader rev range.

After 5 years of development Speedpro has a 30hp MB100 with about 4,500 rpm power spread, posts of the graph and details are on his #6 thread, but 20ish is possibly more realistic to start with. The MB100 is a very good engine.

The ESE thread also has a lot of info, best to scan through the pictures (there are more than 2,000) using the Thread Tools option to find interesting posts and each 10th page starting at page 80 has a collection of interesting bits making it easy to find good stuff. The ESE guys use GP125 engines but a lot of the 2-stroke stuff is pretty applicable to any stroker.

Goodluck

Hilleye

27th September 2011, 22:31

Sorry should have mentioned that it already has the six speed box and read valve with rubber inlet conversion.

Indications on potential are good though.

husaberg

27th September 2011, 23:04

Sorry should have mentioned that it already has the six speed box and read valve with rubber inlet conversion.

Indications on potential are good though.

It looks Like I will be divesting my portfolio of MB and H100 parts inc 2 complete engines and probably 2 extra 6 speeds soon if anyone is interested.plus some random 50 shit. The TZR250 carb (Parallel twin carb) fits nice on the manifold too.with a little sleeve to fill in the gap.CR ignitions fit too.Also try and stick with genuine Honda parts for the internals where you can.
I would quite like to see someone do the air cooled 125 with one to be honest.

koba

28th September 2011, 06:39

Sorry should have mentioned that it already has the six speed box and read valve with rubber inlet conversion.

Indications on potential are good though.

Is the exhaust port still as original?

You should see a good gain on these just by grinding to ease the bumpy bit where they transition from the steel liner to the aluminium outer part.

Be very careful about making it bigger though, You don't want to get it wrong.

Also make sure the bits that the ring touches stay as a nice working surface for the ring.

Yow Ling

28th September 2011, 17:39

The carb on your bike is a TZR2501kt, on a TZR250 it flows enough air for 25hp so that probably isnt the problem. Before you bought it I think it tangled a ring in the exhaust, the old rebore guy declared it rooted, but I think it was tidied up and put back on. you may be better off starting over with a new barrell.
I think my story is pretty right. wont take long to check

Hilleye

29th September 2011, 06:46

Ah, the truth comes out.

Anyone got a spare MB100 barrel they want to sell?

Kickaha

29th September 2011, 07:00

Ah, the truth comes out.

Anyone got a spare MB100 barrel they want to sell?

Buy all Husabergs stuff, that'll give you spares for the rest of your life

F5 Dave

29th September 2011, 10:40

Pete Sales at Total Motorcycles near Palmerston North does a very nice basic port setup for reasonable money. He could spin the head as well for a nice combustion chamber.
. . .
& talking of chambers he's made the odd MB100 expansion chamber as well if you want a decent set up with little risk.

Have to be careful when making a reed setup not to put the carb on too much of an angle. This is easy to upset using a conventional carb saddly such as the very nice flatslide keihin Mike suggests. That 1KT carb should flow well enough for the time being & is angled down ok combined with an old Yam reedblock & inlet rubber should put the carb on a decent angle. I did have problems with a KR250 carb which uses the same casting as the TZR carb that only manifested on long tracks where it ran out of fuel just after the main straight on 'Puna B track springs to mind. if this happens come back & I'll tell you how to fix it, but the TZR carb is probably better.

Grumph

29th September 2011, 11:47

For long circuits an ignition which doesn't have the high rev retard is mandatory. Not so important for kart tracks which favour mid range.

An alternative to increasing inlet port area is to put ports in the rear skirt of the piston giving 360 deg timing regulated by the reeds. Works to lengthen small end life but shortens piston life...swings and roundabouts. Very good power though....

Motorcycle exhausts - Zorsts - do a good MB100 chamber.

Air cooled 125...done that, goes well.

F5 Dave

29th September 2011, 14:03

Not so re the kart tracks. One finds that in between corners with low gearing you can run out of revs & not want to shift up. If the power tails off abruptly (as my 50 does) it limits your choice & slows you down.

Putting holes in pistons while can be useful is a bit late in the stroke & inlet area is easily added either side. Further, into the transfer area around the barrel is possible with some case porting, but have to be careful with sealing the barrel after.

125 aircooled on an MB cannot be done purely with a boring bar. The steel runs out & you are in ally in some parts of the bore, or so I am told, I can't see how you could plate that. You could of course stroke the crank & just bore to 52mm. Not sure what DC did to his bike (& I'm wondering who Grumph is at the moment).

Buddha#81

29th September 2011, 15:35

Not sure what DC did to his bike.

I'm not 100% sure but its 118cc running a early aircooled cr125 piston, not stroked at all. Also from memory he lost top end hp but it become easier to ride (less peaky) after going to the big bored, carb restricted option.

F5 Dave

29th September 2011, 17:00

Actually I might rescind my comments a little. A 54 bore would take you to 113cc & perhaps the guy who told me was trying to hog out to 125 went through. That being said it must be whisker thin at 54mm or seemingly a ticlkle bigger for 118.

bucketracer

29th September 2011, 17:47

247623

Red line is Speedpros 30 hp MB100, note the wide power spread.

Blue line is TeeZees attempt with a GP125 but he gave up on it because it didn't look like it was going to be very rideable around a tight track.

The Green line is TeeZees Suzuki GP125 running a 24mm carb and he believes he will do better with it because it will be easier to ride on a short tight track than his 30hp but peaky engine.

HP is not everything, as well as hp you need a good power spread like Speedpros.

Hilleye

29th September 2011, 18:09

Right, I've stripped the barrel off and found piston is only running one compression ring. Is this standard practice or a dodgey legacy of the last owner (given what Yow Ling has said)?

Carb is essentially only very slightly canted forward with the rubber inlet manifold setup. Running 25:1 Avgas/2T mix. Only thing I've noticed with respect to fuel starvation is when the fuel tank runs low on gas the float bowl doesn't fill on right hand corners, but I think that is down to the fuel pick up point from the tank and the routing of the fuel line, nothing else.

Fuel tank outlet is on lower left side of tank, fuel pickup on carb is right hand side. Fuel line drops below level of fuel intake on carb (might be able to be changed). When fuel level gets low, fuel pressure drops, fuel wont flow left to right across the bike (centripedal force and all that) and then up to carb fuel pick up, so supply is interupted. Just need to keep minimum of 3 ltr in the tank to stop this, unless anyone knows of a suitable carb that has a left hand fuel pickup.

Yow Ling

29th September 2011, 18:34

post some fotos, we all want to see wots in there

Hilleye

29th September 2011, 19:25

Alright so I'm definitely wrong about the rings. Its actually been a while since I had the barrel off and I appear to have made a mistake. I therefore retract any statements that infer the previous owner was dodgey. (but I'm sure I only saw one last time because I remember thinking that's weird).

So carb setup and fuel line routing are shown as is the exhaust and exhaust port. I'm away this weekend, but will endevour to get inlet port and internal cylinder photos up as soon as possible.

247634247633247632247631247630

Kickaha

29th September 2011, 19:29

I therefore retract any statements that infer the previous owner was dodgey.

Don't bother with any retractions because he definitely was
:msn-wink:

It used to go pretty good before it got Dawsoned

F5 Dave

29th September 2011, 21:18

hmm, that looks a bit familiar. Didn't the rear shocks make a kind of pyramid shape inward? I just remember on my way past every few laps on my 50:innocent:

bucketracer

29th September 2011, 21:25

Only thing I've noticed with respect to fuel starvation is when the fuel tank runs low on gas the float bowl doesn't fill on right hand corners, but I think that is down to the fuel pick up point from the tank and the routing of the fuel line, nothing else.

A possible, sort of cure could be a small header tank made from a cheap car fuel filter.

247647

This is something TeeZee made from a SuperCheap filter. The trick to making a filter into a header tank is to drill a small hole in the top and cut a small piece of the fuel line connector barb off and glue it into the hole for an air vent. The fuel comes in through the black hose at the top and the air escapes up the clear plastic vent hose that runs from the vent to up higher than the fuel tank. In this picture the outlet at the bottom of the filter/header tank has not been connected to the carb yet.

With a breather the filter now works as a filter and header tank, something similar should last long enough to get you around r/hand corners and then refill again going down the straight.

247652

TeeZee also fitted a tap to it, this makes it easy to take the carb off without spilling all the gas in the header tank. He fitted the header tank to his bike because we were seeing air locks/bubbles in the fuel line during heavy runs on the dyno, it works a treat, now the line stays full all the time.

speedpro

29th September 2011, 21:41

husaberg

29th September 2011, 21:49

I'm not 100% familiar with those carbs but I think the little white plastic fitting next to the fuel inlet hose needs to be blanked off. Without that you will have a hard time tuning it. Otherwise it looks OK(ish). Make the effort to get a good pipe on it and if you want get a port rubbing and send it to me. I'll run the software over it and see where it's at. If it's old-school you may be better off dropping the cylinder and reporting.
Looks like a reasonable sort of bucket to get going on.

Not sure on that fitting. The only one at the back I can remember was the power jet. Although as the carbs are matched pair they may not be identical left and right.
On my bike with a TZR carb and a RD inlet I put a little PVC spacer to take up the gap in the inlet rubber as the TZR has a shorter spigot than the RD carb does.
The top bung is the oil feed is blocked off. Dave will say to put a boost bottle there (Just Kidding Dave) leave it as is.
He asked about the one ring earlier that OK I only used to run one the theory was less wear on the cylinder and less friction I doubt if it really makes a measurable difference by I couldn't resist doing it.
Is it a quirk of the picture or is there a spacer bellow the barrel.

EDIT the PJ was Brass I will have a look in the shed.
Ps put a uni filter on it I can feel the dirt getting in there already.

PS the 125 can be done using a non competition barrel with a 57mm piston its available from new too.

The MB50 ignition has a high speed retard function the Mb100 has a advancing ignition.

The pipe dimensions also looks a little odd by eye. But the pipe doesn't care what it looks like I guess.

Please post a pic of the full bike I can't figure out the frame.

Kickaha

30th September 2011, 05:36

Please post a pic of the full bike I can't figure out the frame.

The frame is an MT125 copy, there were two of them built and they raced in the NZ 125 champs back in Medieval times

F5 Dave

30th September 2011, 08:18

. . .
PS the 125 can be done using a non competition barrel with a 57mm piston its available from new too.
. . .
Are you sure? Dave D said he went through the liner trying to bore it. The steel is a wasted shape with ally cast over so it is hard to tell where the least thickness is.

koba

30th September 2011, 09:34

Looks quite good, reasonably well developed.

I would guess there may be one or two small things holding it back, the pipe may be one, looks a bit long and shallow tapered for much power but Its always a guess just looking at photos.

What else ain't working right is the million doll.. oh wait, this is buckets... the $400 question.
(I had to think of an amount that makes me go "gosh, that alot of coin")

Exhaust port ain't standard but doesn't look massive either. (observation only, I'm not ready to start handing out advice there!)

I think speedpro is correct about the white plastic bit. Some similar carbs have a bleed screw there instead, I've had better results with that setup so far but there are likely to be other factors involved.

Speedpro's offer is a good one and it would be well worth taking him up on it.

Buddha#81

30th September 2011, 11:48

Are you sure? Dave D said he went through the liner trying to bore it. The steel is a wasted shape with ally cast over so it is hard to tell where the least thickness is.

if you have a spare barrel bring it to the BOB i can ultasonic measure the thickness for you.

koba

30th September 2011, 12:19

if you have a spare barrel bring it to the BOB i can ultasonic measure the thickness for you.

Phoo aye! <tenchar>

Buddha#81

30th September 2011, 12:47

Phoo aye! <tenchar>

Flash as down here!

husaberg

30th September 2011, 17:13

Are you sure? Dave D said he went through the liner trying to bore it. The steel is a wasted shape with ally cast over so it is hard to tell where the least thickness is.

Very sure, if all the net research stakes up and it is reasonably collaberated on more than a couple of sites In fact I may be willing to bet a R6 rear caliper on it. Dave?
Do you want a picture?

Husaberg PS the 125 can be done using a non competition barrel with a 57mm piston, its available from new too.

Read the post again before you make the bet Dave. Because I love R6 Rear calipers.

PS Who is Dave D?

Henk

30th September 2011, 19:06

PS Who is Dave D?

Dave Diprose

Hilleye

30th September 2011, 20:30

.

The MB50 ignition has a high speed retard function the MB100 has a advancing ignition.

Please post a pic of the full bike I can't figure out the frame.

Electrics are a mystery to me. Do I want and advancing or retarding ignition? I assume advancing.

Has anyone just bunged on an RG150 or NSR125 CDI and seen what happens? What does one of the programmable ignitions cost?

Will do a full bike pick with inlet and cylinder photos.

husaberg

30th September 2011, 20:47

Electrics are a mystery to me. Do I want and advancing or retarding ignition? I assume advancing.

Has anyone just bunged on an RG150 or NSR125 CDI and seen what happens? What does one of the programmable ignitions cost?

Will do a full bike pick with inlet and cylinder photos.

I used to think I knew the answer to that question. Now I am not so sure.
The more that I learn the more I realise that I didn't know as much as I thought I did.

Get Wob to answer the ignition question and he will be able to obtain a Ignitech ignition for you. I have sent him a link to the thread.

Ps I have tried a static CDI unit on the MB I didn't run that well as it broke down at revs as it was from a dirty 4 stroke that ran at half engine speed and couldn't hack the pace.
There is a page which I will post that explains the ins and out of basic ignition and winding coils etc http://www.btinternet.com/~jhpart/bkns125a.htm

speedpro

30th September 2011, 22:03

speedpro

30th September 2011, 22:05

Regarding oversizes, Dave D tried a 54mm piston in a MB100 and ended up going through the sleeve into aluminium, just.

TZ350

1st October 2011, 07:30

PS the 125 can be done using a non competition barrel with a 57mm piston its available from new too.

"From New" could this be the clue?

husaberg

1st October 2011, 07:42

"From New" could this be the clue?

The highlighted bit was intended to give it away.
I may have been a bit too subtle. I wonder if I have let some sort of cat out of the bag.
As Dave has for some reason got his back up Plan already in place In the event that if for some reason just in case his 100 is not ready for Taupo?.http://http://www.kiwibiker.co.nz/forums/showthread.php/104668-Will-I-get-my-100-ready-in-time-for-Taupo/page10 Was this it.

I was aware Honda has made MB5/MB50 and MT variant and I was aware of the MB80/MB8 models as well as the of course the H100/Mb100 Models.
Well I had always assumed the MB8 was a big bore 50 well it appears to be a debored 100 according to the pretty much all the specs I have been able to find this makes the MB8 a 45mm x 49.5mm = 78cc.
I know the net is full of duff info but this seems to be highly likely to be correct as it is repeated consistently.
I can see this info is a little boring but there is big bore kits that are not competition parts available for the MB8 one of them see pic below offers a 57mm kit (it will I guess) be on a low state of tune but has a nice looking piston.(which could be a display pic)

http://www.moped-museum.de/sonstige-mopeds/honda-mb5-mb8.htm
http://www.50cc.nl/frameset_eng.htm
http://www.scootparts.nl/Cylinder-Athena-Honda-MB/MT/X-80-125cc-Cilinders-ed-6699/en/product/66715/
http://translate.google.co.nz/translate?hl=en&sl=nl&u=http://en.opvoeren.com/part.asp%3FO%3DEurocilindro-(Athena)125cc-Honda-MB8/MT80_571&ei=HomGTrrBG_C0iQepvcWmDw&sa=X&oi=translate&ct=result&resnum=3&ved=0CCkQ7gEwAjgK&prev=/search%3Fq%3Dathena%2Bcylinder%2Bhonda%2Bmb8%26sta rt%3D10%26hl%3Den%26sa%3DN%26biw%3D1280%26bih%3D82 7%26prmd%3Dimvns

Re the limit for the STD cylinder the Ryteching site (which sadly looks like it has died now, but I have saved some info off it). Used to list a 53mm OS piston for the MB100.
That I would guess is the limit for the STD cylinder.
(Ryteching Info now posted)
I have found some bits of info on this site are wrong as in some typos but it was a great site for looking for specs of pistons.

As you guys are intending to measure a MB100 cylinder measure the h100 as well as there are some subtle changes and a few not so subtle design detail differences between the engines.

The Japenese BTW are credited with the bonding process (I would say they perfected it for mass production) but I believe invented or developed at least by the brits in the 50's... Wellworthy? and probably earlier by the Yanks. There seems to be a patent in 1929.
It was common of Brit race 4 strokes. Alfin. Including the Villiers Starmaker 2 stroke.

The sleeve is odd shaped (sometimes corrugated for want of a better description) mostly I believe to increase the surface area and make sure it stays in place and I believe its is thicker at the spigot to provide support at the base which isn't as well supported.

F5 Dave

1st October 2011, 07:56

I've known Dave for well over 20 years & if he says it goes through, then it goes through. He isn't one to ignore details & if anyone has met him they'll know what I mean. Big bore kits may have sleeves, even new barrels, who knows.

TZ350

1st October 2011, 08:25

Yes, I have found that too, going 2mm OS is ok 4 is dodgy and I have gone through the liner on RD cylinders this way. It seems that the alloy/liner bonding process allows the Japanese to run very thin liners and the liners are wasted too or have ripples around the outsides and I wound up with a series of rings in my RD cylinder. You can often see the liner in the spigot is thicker than the liner you can see in the port window.

Husenburgs special completely Bucket legal aftermarket MB 57mm oversize cylinder looks interesting, its truly another gem gleened from the mysterious internet.

dangerous

1st October 2011, 08:42

Alright so I'm definitely wrong about the rings. Its actually been a while since I had the barrel off and I appear to have made a mistake. I therefore retract any statements that infer the previous owner being dodgy
That be me... Havent read all so fill me in, all i can say is i did no work personaly to the engine see bren chch for that.
Over the time i had the bike it went beter and beter till i decided it was time for a freshen up as it had done a few seasons.
As yl said the oll boy that does our re bores wasent happy with the exhaust port being squared of, he was worried it might hook a ring up (it never did) so in order for him to hone for a fresh piston brenn chch had a go at the port.
Un fourtnuatly imho this changed the port timing to much and i never got it tuned right again, yes i did all the carb tampering to the best of my knolage. I would look at starting again with a new barrel.

bucketracer

1st October 2011, 13:40

On page 200 there is a simpler 23 rwhp setup using a RG250 chamber modified to RM125 specs. And on this page, the basic details for 27rwhp

Suzuki GP125 but might be worth a look ......

bucketracer

1st October 2011, 14:31

247708

A better view of the filter modified to be a header tank by adding a breather.

bucketracer

1st October 2011, 16:09

Because a few people have asked about the GP engine, to save wading through 270 pages, these links go to the more relevent posts about the 27hp engine. Different link collections can be found on the decade pages 80-90-100.....260 etc.

238154 27rwhp 1978 Suzuki GP125

A direct line to a bunch of Team ESE engine development posts ..........

F5 Dave

2nd October 2011, 08:59

. .
As Dave has for some reason got his back up. . . . .

Have I? I was just saying that I wouldn't overbore a 100 too far, I wasn't throwing any sort of hissy fit:crybaby:, - the 80?, who knows?

husaberg

2nd October 2011, 21:41

I've fitted various ignitions over the years and they have all seemed to be good. I've now got an Ignitech. Funny thing is that I can now alter the timing to anything the bike wants and it seems that apart from one little point way up in the powerband a flat timing curve is what it wants. Fixed timing would seem to be OK, as tested on the dyno on my motor.

Interesting I always were lead to believe the retarding at high revs a little increased the over rev potential a little. When You say way up is that where it is?

speedpro

4th October 2011, 07:23

13,000rpm(ish).

That might change with the new carb when the power jet is turned off.

koba

4th October 2011, 15:44

Bike is running a Mikuni carb that's been machined out to 27mm and what looks like a home made exhaust system with a can of unknown origin.

Just a thought I had on this - What is the carb off? Has it run well with this carb before?

It sounds from your first post that you are having trouble jetting it lean enough not to bog but rich enough to not cook.
Could that be If the Air fuel correction doesn't match the current motor because it's off a 4-stroke or something? (making it too rich at some points and too lean at others)
(Unfortunately I'm only coming up with more questions rather than the answers I'm sure you want!)

What do you base the "too lean" on AF ratio meter on the dyno?

(EDIT: I can kind of see that on your pic but my eyes aren't the best..)

koba

4th October 2011, 15:51

Now I worked out the zoom I can see that pic better.

Was that thingy speedpro pointed out blanked off or still open?

If it was open it would be interesting to see how another dyno session goes with it blocked off.

Hilleye

4th October 2011, 18:57

It's currently still open. I think it's just the oil injection inlet. You reckon that could flow enough air to make a difference?

Yow Ling

4th October 2011, 19:27

husaberg

4th October 2011, 21:08

I think the white plastic fitting that Speedpro refers to needs to be left alone , it has feelings too!
Here is a pic of a standart TZR250 carb with a little hozey thing attached, it goes into a gallery which turns right just behind the blanking screw at the bottom of the bellmouth, at the bottom of this gallery is a small jet , I guess its an air jet as there is no airscrew on the carb I have.

Maybe of interest is the brass nipple beside the fuel in hole what is its job, is it hidden in hilleyes picture?

This is the same type of carb as Hilleye has.

247926
247927

I am with Yow on the Plastic vent. It is the same as my one. It was always left open to the catch can on my bike I have looked for my carb notes and it says I always ran between a 210 and a 230 main in mine .But mine was a higher state of tune I guess.

My carb which was a bit trick in the very early 90's Well that's what I told myself.It bloody cost $75 then which was about 2 days apprentice wages at the time.
It was always ran with a foam filter (Uni) and came without a throttle cable and a choke the STD MB100 Keihin choke fitted just fine and the only cable I could find to suit then was a DT200 one.
I read somewhere in PB the max they can be bored was 29.2mm or similar I imagine that would be a real mission. I have some info on these carbs on the computer somewhere it came from a tzr250 tuning story if I can find the site I will post it if it has any relevance.

The great thing with these carbs is they suit the angle of the cylinder with the RD reed rubber and are short and have a huge fuel fitting as well.

speedpro

4th October 2011, 21:39

husaberg

4th October 2011, 21:47

It's not oil injection and I'd be surprised if it was left open or had a jet in the line. Why would you put a jet in a line rather than direct in the carb. It would have been a controlled air bleed to the emulsion tube. I'd lay money on it needing to be blocked off.

I don't rememember Yow or anyone saying it had a jet in the vent?

Here is the f3 carb mods I would not say all his mods are Nesercary but here is the Naughty boy page I couldn't get the page to work on the net but I was able to piece this together with a page I had saved.

But as I said above my was never blocked off on my bike that had the same type of motor and the same carb. The power jet was never blocked off either.

koba

5th October 2011, 06:09

You reckon that could flow enough air to make a difference?

A tiny leak can cause havoc with correct carberretion. Yes, very much so.

koba

5th October 2011, 06:12

I'm not experienced in dyno tuning but from that graph you posted, the meagre power output and tuning problems you seem to be having I'd suspect there is something wrong somewhere. The carb would be the first logical suspect.

F5 Dave

5th October 2011, 09:46

I'm with Mike, block that puppy.

There is an jet to the emulsion tube & the pilot system at the front of the bellmouth. Why have another air passage?

Answer, probably open a solenoid to lean it off when at idle to pass an emissions test on Jap models. My RGV 32mm carb has the same doofer & there seem to be several versions of RGV carbs even between the usual VJ21 & 22 models presumably for different markets. I couldn't get it to run better with it open or even with a tiny jet in it as I attempted to use this for tuning to see what it liked best.

husaberg

5th October 2011, 16:50

I don't remember Yow or anyone saying it had a jet in the vent?

Here is the f3 carb mods I would not say all his mods are Nesercary but here is the Naughty boy page I couldn't get the page to work on the net but I was able to piece this together with a page I had saved.

But as I said above my was never blocked off on my bike that had the same type of motor and the same carb. The power jet was never blocked off either.

Right here is a copy of the TZR race kit Manual for the carb.

It does say as I alluded too earlier to block it off, but has anyone confirmed that the fueling is wrong on the bike as it is now?

If the fueling is ok now. I can't see how it will gain any HP. Unless the fueling is crap at the moment.

I should probably point out this was for this model carb what ever it is and no doubt the Crafty Japanese made a few changes during the model Run.
Maybe Hilly should give us a run-down of the carb jet specs as they are now.
I see the KR250 the Rotary Reed valve original one had similar carbs 28mm downdraft SS mikunis.
So if Hillys carb is off one of these. All bets with regards to jetting are off as the disk valve will probably have a four stroke style Emulsion tube at a guess.

I have posted the rest of the Naughty boy file as I like shiny milled billet stuff mmmm.....shiny

The ex Naughty boy racing site is renamed and is here not a bad site intersting stuff Mainly Yamaha Shame.

http://www.speeddemonracing.com/articles.html

F5 Dave

5th October 2011, 16:57

ahh. so the main belmouth one is blocked? My RGV one wasn't for the reasons I explained. This seems like a sensible mod, or alternatively one could just put the drilling elsewhere, but easier & cleaner to drill then epoxy up the hose fitting.

ON TZR carbs with rubber hose fitted to feed the powerjet (which doesn't seem to flow particularly well without the airbox as it isn't an extended tube) I have found pilot jets stuffed in the rubber tube. I doubt Yamaha fitted them there, but I've found them on about 3 carbs. Naughty production racers. Actually I have about 3 different TZR type carbs & some gad removable jets in the airjet area.

Yow Ling

5th October 2011, 17:42

Hilleyes carb is off a TZR250, the one that I ride in buckets with a FXR motor in it.

koba

5th October 2011, 18:29

If the fueling is ok now. I can't see how it will gain any HP. Unless the fueling is crap at the moment.

Yeah, very true.

It doesn't look like everything adds up right from the way I read all the posts, like it isn't fueling properly all the way through the range. BUT also as stated earlier, I am no expert.

Could it also be that the other aspects such as pilot jet and slide cutaway are wrong for the motor and haven't been addressed properly?

(Not trying to be a cock, just raising points that may or may not have been overlooked.)

speedpro

5th October 2011, 18:35

My 34mm carb had the same fitting and it wouldn't jet up on the dyno. We tried it open and with various size jets fitted. It cleaned up immediately and responded to mainjet changes when we blocked it off.

husaberg

5th October 2011, 18:36

Yeah, very true.

It doesn't look like everything adds up right from the way I read all the posts, like it isn't fueling properly all the way through the range. BUT also as stated earlier, I am no expert.

Could it also be that the other aspects such as pilot jet and slide cutaway are wrong for the motor and haven't been addressed properly?

(Not trying to be a cock, just raising points that may or may not have been overlooked.)
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=247520&d=1317112166&thumb=1

I can be a cock without trying

Just read first post must have missed that Whoops

Hilly Positives from the session on the dyno were:
1. The bike is no longer in grave danger of seizing because it was running way, way, too lean.
2. I actually know where its making power and can now ride it accordingly.

Negatives:
1. Bike is making less power than expected and is quite peaky. Peak power is also being made quite low at around 9200rpm. Exhaust seems to be the culprit on this.
2. Carb seems to be too large for the bike. Diagnosed from:
No power increase with a jetting increase.
Jetting also can't be increased as carb won't flow enough air. Raising the needle to flow more air (to allow bigger jet) just causes bogging issues.
Unable to reduce the jetting size without compromising the fuel/air ratio and placing the engine at risk

What I don't have is an objective point of view of what can reasonably be expected from this motor and where I should start to try and improve it. I've heard figures of upto 30hp being bandied around, but would be happy with a little more than what I'm getting over a much broader rev range.

Bike is running a Mikuni carb that's been machined out to 27mm and what looks like a home made exhaust system with a can of unknown origin.

But The issue as I see it is the bike isn't making HP as hilly says the carburation is obviously amiss. if the symptoms are right.

But the TZR250 carb has been successfully used on other bikes including many a MB100 making more power without these problems.

Is there other problems with the condition of the carb etc rather than design faults.
Has the boring of the carb made something amiss is it sealing around the slide for instance is the slide reaching full lift a full throttle the list goes on
Is the fuel line hard is the filter in the tap blocked restricted as on the stock MB5 tank with a mild motor the tap was effectively the defacto main jet even when drilled out is the float height correct is the needle and seat ok are any airways blocked etc.
Note I always used a foam filter.

No one has mentioned reeds either. What reeds does it have. Are the stops std. Out of control reeds do all sorts of weird things to power and fueling.

The Ledar kits sold for these bikes (TZR) when the airbox was eliminated required a filter spacer it was one of the few bikes that needed one.interesting,

Link here for Manuals for TZR250

http://http://www.speeddemonracing.com/articles.html (http://www.speeddemonracing.com/articles.html)

Hilleye

5th October 2011, 18:42

Right here is a copy of the TZR race kit Manual for the carb.

It does say as I alluded too earlier to block it off, but has anyone confirmed that the fueling is wrong on the bike as it is now?

If the fueling is ok now. I can't see how it will gain any HP. Unless the fueling is crap at the moment.

I see the KR250 the Rotary Reed valve original one had similar carbs 28mm downdraft SS mikunis.

Ok, cos I put it on the dyno the fueling is as good as it's going to get, but it's by no means perfect. It's still leaner than optimal.

Basically Brendan at Dynoworx said "We have lost control of the main jet." What he meant (because he explained it to me) was that there was no longer enough air flow through the carb. When we tried to improve the air flow to further improve the A/F mix by raising the needle the bike started to bog. When we reduced the main jet size the A/F mix started to lean out and no increase in power. Now this may not necessarily be the fault of the carb, it could be any number of factors, but we'll elminate them one at a time.

So far:

The plastic bit on carb has been identified as needing to be blocked off along with some other bits. Will follow instructions on how to rectify.

Port timing on the existing cylinder has been identified as potentially suspect. Will replace and get porting done properly.

Exhaust might not be optimal and might be restricting power because needs to be produced quite high in the rev range. Will experiment with alternatives. Question: What is the likely impact of throwing a 125cc exhaust on (Aprilla RS125) ?

Might need adjustable ignition to allow bike to rev into rpm band required to make good power. Will look into cost of replacement.

Bike will be raced as is for BoB (honestly not sure more power would make too much difference at this time), but essentially I've now got areas requiring development.

I actually owned an old KR250, fantastic bike. Powerband hit like a sledge hammer often lifting the front wheel. Reliability wasn't its strong suite though.

F5 Dave

6th October 2011, 08:17

yeah I'd try block the tube & see if it responds to mainjet changes with a couple of dyno runs. Get everything else sorted before worrying about an adjustable ignition, there are probably only 1/2 doz buckets in NZ with those & most of them very recent.

Porting & pipe? Well best to see what you have got now, measure up. An Aprillia 125 is a roadbike & probably isn't a fantastic start point.

husaberg

8th October 2011, 21:06

MB5 MB100 H100s Primary drive all 17x70 =4.117
1st 3.17 3.083 3.08
2nd 2.06 1.882 1.78
3rd 1.50 1.400 1.27
4th 1.17 1.130 0.96
5th 1.00 0.960
6th 0.88

Supplement to service manual that covers six speed gearbox I will post below.

Plus an ancient H100 pipe design. Blame Bell and the fact that I did it 15 years ago if its a bit dated

MB5 ignition
Ignition timing "F" mark 19 +or- 3 degrees BTDC @ 3000 rpm
Full retard 10 +or- 5 degrees BTDC @ 7000 rpm

MB100 15 + or - 3 degrees BTDC @3000 rpm then advancing thereafter according to the blurb in the Hayes manual

husaberg

8th October 2011, 21:54

Hilleye

14th October 2011, 19:26

Just finished practice today. Bike was running okay until the end. Then it stated making a clunking death rattle sound on shutdown. :shit: Started up and ran alright again though, so hopefully it'll last the day tomorrow. :sweatdrop Wallace, who was there at the time said it sounded like it might be a loose crank. If this was the case any ideas how long before the time bomb explodes?

This has demonstrated to me that I need a spare engine though. Anyone selling one?

Thank you all for the help with the bike, your posts have been exceptionally helpful.

Kickaha

14th October 2011, 20:12

This has demonstrated to me that I need a spare engine though. Anyone selling one?

Try Diesel Pig, he's developing a new engine so may sell off his MB stuff

koba

15th October 2011, 07:12

If this was the case any ideas how long before the time bomb explodes?

Don't risk guesses.
Pull it apart, find the problem (and check for any others) and fix it. If you can't, get someone else to.
It could be a cheap and easy fix now but a whole new motor job with 10 seconds more running time.

koba

15th October 2011, 07:14

Once an MB has been put together properly with new bearings and the like it should last for ages with little or no trouble.
Often rust on bearing surfaces from sitting around in sheds will cause catastrophic failure.

F5 Dave

15th October 2011, 20:07

Nah nah, it'll be alright.

except it wasn't. Anyway nice meeting you.

Hilleye

15th October 2011, 21:14

Bastard, she started to warm it up, sounded ok at the time, little death rattley on shut down, but same as yesterday. Started again and died waiting to go on the track. Then wouldn't start and stay running for more than a few seconds, even on the roller, clunking and backfiring just got progressively worse.

Pulled it out this evening, haven't split the case yet, but can feel about 1 - 2 mm of lateral play in the crank. I'm assuming that this means the main bearings and hence crank seals have gone.

Small end and big end feel fine and were covered in 2T mix so pretty sure they were being well lubed. No play in either bearing. No signs of seizure on the piston. Nothing in the barrel either. Will post photos of everything tomorrow to give you all a good look at the whole package. Your advice will be appreciated from that point onwards.

Real bitch was I was lending it to a mate so he could experience and potentially get into bucket racing, needless to say he's been put off two strokes by the experience, but hopefully not buckets all together. And I myself have come to the conclusion that you need to pack an engine for each race, just to be safe.

TZ350

15th October 2011, 21:26

Real bitch was I was lending it to a mate so could he experience and potentially get into bucket racing, needless to say he's been put off two strokes by the experience, but hopefully not buckets all together. And I myself have come to the conclusion that you need to pack an engine for each race, just to be safe.

Pity your mate missed out, but once you have properly overhalled that MB engine and got it sorted it should be very reliable, they are well proven engines.

Hilleye

15th October 2011, 21:54

...but once you have properly overhalled that MB engine and got it sorted it should be very reliable, they are well proven engines.

Is that like one of those Tui adds?

husaberg

15th October 2011, 22:24

Pity your mate missed out, but once you have properly overhalled that MB engine and got it sorted it should be very reliable, they are well proven engines.

Id go along with that. decent bearing and a quality port job and proper jetting and they last well.

I would be interested to see if the stator has touched the magnets as I had a mag side bearing go once but upon inspection it was from a bloody wheel bearing or similar it definitely wasn't a C3 bearing.

Kickaha

16th October 2011, 05:38

Is that like one of those Tui adds?

No it isn't

I've seen those engines easily do a season (or more) without being touched

TZ350

16th October 2011, 05:58

Is that like one of those Tui adds?

Nope .... but expecting an engine that has had a thrashing for how long? then left neglected to last again without some attention may have been a bit much.

It might be Buckets but its real Racing, for racing, you need a race ready engine, you can't expect to cut corners and last.

If you overhaul it with good parts like slotted rod, silver bigend brg, decent C3-4 brgs (for side clearance) new oil seals and a re-bore with a decent piston. Read everything you can about how the ports should be finished and if you still have the big heavy original flywheel ignition loose it. Good ignitions are much cheaper now and if you don't want to mess with a programmable get a straight line MX ignition, something from Ebay like the stator Speedpro is using would be the go. CC the head to get the correct (or at least known) compression ratio and set the ignition and main jet up on a dyno if you can. Modifying the clutch pack like Speedpros wouldn’t be a bad idea either. There has been a heap of good info posted on your thread.

And there have been a lot of very good MB100's built, they are a proven engine.

Get the details right and you will have yourself a really reliable and fast bike.

Please post photos and comment about your progress as you go, its great to watch someone elses race project progress.

dangerous

16th October 2011, 06:04

Hilleye

16th October 2011, 06:30

Hilleye... how come the bike was on the back of the ute yesterday? Think earler in the thread the squared off ex port was mentioned, just found some pics including this one, looks like it has just had a hone (still got a spear piston for the current over size if ya want it) still some what out of shape but I never had issues with it.

I think bike has run a main bearing.

That picture is what the port still looks like now.

Would definitely be keen on the piston if possible. Heading into town this morning and could pick up at same time.

Buckets4Me

16th October 2011, 08:30

Would definitely be keen on the piston if possible. Heading into town this morning and could pick up at same time.

my engine gp125 witch tz built 6 years ago is still making 18-19 h/p and has only had 1 piston changed in that time

2 strokes when rebuilt well will out last the 4 stroke brethren :shit:

and cost less to rebuild when you bend a valve snap a cam chain or just forget to check the oil :blink::facepalm:

dangerous

16th October 2011, 17:07

my engine gp125 witch tz built 6 years ago is still making 18-19 h/p and has only had 1 piston changed in that time

2 strokes when rebuilt well will out last the 4 stroke brethren :shit:

and cost less to rebuild when you bend a valve snap a cam chain or just forget to check the oil :blink::facepalm:

Interesting... cos after 2 hard out meetings the bike was going the best it had, but I thought a freshen up with new piston and hone would be in order... it didnt run aswell again... morel, dont fuck with if alls going well... but then my luck next meet and it woulda blowen.

I think bike has run a main bearing.

That picture is what the port still looks like now.

Would definitely be keen on the piston if possible. Heading into town this morning and could pick up at same time.

crap... never went near the bottom end and god knows how long since it was done.
Yeah thats how it was after being re ported to round off the squaring and a hone with the new piston as above.
Will look for the other pisto and ring when I get the chance (as per pm) oddly enough just back in from Burnham, so could have droped it off LOL.

Hilleye

16th October 2011, 19:14

Ok, have split the crankcase here are the results. I'll work my way down the engine.

Head.

248661248662248663

Hilleye

16th October 2011, 19:22

Barrel.

Inlet port.
248667248670

Exhaust port.
248668248669

Hilleye

16th October 2011, 19:25

Reeds and inlet manifold.
248672248671248673

Piston.
248674248675248676

Hilleye

16th October 2011, 19:28

Crankcase, gearbox and clutch.
248678248679248680

The attached thumbnail is a picture of a random bolt that fell out of the crankcase when split. If anyone could enlighten me as to its purpose I'd be much obliged. For the life of me I can't find anything that even remotely fits and wonder if it's just been floating around in the oil.

dangerous

16th October 2011, 19:33

Ok, have split the crankcase here are the results. I'll work my way down the engine.
All looks ok so far, the orange discolouring is copper spray I used to use, head looks a bit wet and one side looks like deternation marks or does it just need a wipe clean?
Intakes rugh as guts aye, allways was but it is how it came to me ohh and its a RG250 reed block.
Barrel looking ok tho pic 3 seems a bit odd but Im asuming its what ever you are sitting the barrel on for the photo... not a gouge in it aye?

The attached thumbnail is a picture of a random bolt that fell out of the crankcase when split. If anyone could enlighten me as to its purpose I'd be much obliged. For the life of me I can't find anything that even remotely fits and wonder if it's just been floating around in the oil.AHHHHH... thats were that farking thing went, I knew it wouldent a gone far :shit: actually its a handy item Honda put in the bottom end to prop the reed block up with when taking photos, ya dont get that with a BMW aye...

So... no damage or issues found then, I asume it was this head of a nut that got cought court up in the box?

Hilleye

16th October 2011, 19:40

Crank and conrod.
248682248683248684

Note the patch of rust. I'm thinking after reading F5Dave's post that maybe the bike fell victim to being parked up in Upper Hutt for 18 months without being run. The result being the main and big end bearings have corroded and the two days of practice prior to the BoB was enough to flog them out. Bearing on crankshaft (Mag Main?) had very, very small amount of play in it. One that sits in the case (Drive main?) has quite a significant amount.

Conrod play.
248687248686
Approx 2mm at top. Questions for those that know. Is this excessive? Does it indicate the bearing is worn? Will the conrod need replacing or just the bearing?

Yow Ling

16th October 2011, 20:10

Approx 2mm at top. Questions for those that know. Is this excessive? Does it indicate the bearing is worn? Will the conrod need replacing or just the bearing?
the side play in the small end no concern as the rod is centralised on the crank.
You just buy a rod kit, it has a new rod , big end bearing, crankpin and thrust washers. buy a new small end and new mains. that is what you need
If you send me the crank I will fit all the parts

koba

16th October 2011, 20:23

A new rod should also have oil slots instead of holes and the newer big end bearings are supposed to be better quality than original ones.

That Inlet port looks horrible.

I would guess that head leaks too, the way to fix that is to O-ring it or machine the head and barrel to have a spigot fit that is then lapped. Like an old Volkswagen.

Hilleye

16th October 2011, 20:34

I would guess that head leaks too, the way to fix that is to O-ring it or machine the head and barrel to have a spigot fit that is then lapped. Like an old Volkswagen.

Sorry, with that photo the metal gasket is actually sitting on top. Didn't realise it was there till I put the head down again after taking the photo and it slipped off. Can redo them if you need to see the detail underneath.

Hilleye

16th October 2011, 20:42

You just buy a rod kit, it has a new rod , big end bearing, crankpin and thrust washers. buy a new small end and new mains. that is what you need.

Just go to Honda dealer or is there somewhere else I should try?

TZ350

16th October 2011, 20:52

Just go to Honda dealer or is there somewhere else I should try?

Conrod kit, check with them to see if its slotted. http://www.trademe.co.nz/motors/motorbikes/parts-for-sale/other/auction-415302675.htm

koba

16th October 2011, 21:14

Sorry, with that photo the metal gasket is actually sitting on top. Didn't realise it was there till I put the head down again after taking the photo and it slipped off. Can redo them if you need to see the detail underneath.

You will see signs of leakage if it is. If you look at it carefully you will know it when you see it.

EDIT: looks like it is leaking out towards the head mount, hard to say from here though, have a good look and work out why that side is all mucky.

That rod kit is a 'long (brand) rod'. The one I bought from the same place was slotted, even though when I asked he said it wasn't.
Dave had one snap ages ago so can't be sure about quality but I bought one...

Hilleye

17th October 2011, 05:34

You will see signs of leakage if it is. If you look at it carefully you will know it when you see it.

EDIT: looks like it is leaking out towards the head mount, hard to say from here though, have a good look and work out why that side is all mucky.

I think it's only mucky because it had been sitting on the bench with the remants of the gearbox oil. Some just got smeared on it when I picked it up. I will check for leaks though.

Hilleye

17th October 2011, 06:25

Conrod kit, check with them to see if its slotted. http://www.trademe.co.nz/motors/motorbikes/parts-for-sale/other/auction-415302675.htm

Thank you. Much appreciated.

F5 Dave

17th October 2011, 08:59

husaberg

17th October 2011, 20:06

The guys are right, anything that sits around can be suspect if not stored in oil.

My long rod in the MB50 snapped, but that can also be caused by over loose side clearance (I learned from the excellent Eric Gorr book), so the jury's out on long brand rods, however I do know from a mate in the bike biz that they used to do a lot of farm bikes with long rodkits & they'd die again until they started to throw the bearing away & use a genuine one.

As Koba states, that rod is the original Honda one from the 80s. New parts all round & you'll be set for years.

The rod that i replaced out of my h100 was the slotted style I assume it was std
Maybe its another example of the subtle differences between these engines.
The H100 followed the Mb100 but was a for the most part less racy design points ignition and milder port timing etc.
Assuming the Honda rods are still available unless a higher spec legal one can be found I would stick with a Genuine one.

Out of interest what was Speedpros one in his avatar it was obviously not brittle.

koba

17th October 2011, 21:34

The rod that i replaced out of my h100 was the slotted style I assume it was std
Maybe its another example of the subtle differences between these engines.
The H100 followed the Mb100 but was a for the most part less racy design points ignition and milder port timing etc.
Assuming the Honda rods are still available unless a higher spec legal one can be found I would stick with a Genuine one.

Out of interest what was Speedpros one in his avatar it was obviously not brittle.

The genuine replacement rods are slotted. The MB originals just have holes.

dangerous

18th October 2011, 05:01

Just go to Honda dealer or is there somewhere else I should try?
Its a farking shame TonyB's Motoequip failed due to a hot shot up north, he could have suplyed piston and rod kits of qualaty at decent prices...

And listen to YL below, I practely learnt every thing I know about strokers from him... pitty I aint a very good listener

the side play in the small end no concern as the rod is centralised on the crank.
You just buy a rod kit, it has a new rod , big end bearing, crankpin and thrust washers. buy a new small end and new mains. that is what you need
If you send me the crank I will fit all the parts

F5 Dave

18th October 2011, 08:13

Koba's full of it. good information I mean.

I suspect they just evolved the rods & that became std as Honda won't be making them themselves. I've seen one slot at the bottom & a slot either side as well.

The H100A & H100S are a little different, the S has points, not sure about A.

husaberg

18th October 2011, 16:01

The H100A & H100S are a little different, the S has points, not sure about A.

I said that above Dave:facepalm:
In front of me is a std Gen H100s Rod.
It has slots either side at big end and two holes at the top.
At 11 and 1 o'clock

I do note the bearings are colour coded i will post the specs. H100Sd

The observant amongst you will note the 360 centre code (Model) on the thrust washers on the big end.The 360 code refers to the Cr125m very similar to the Mt125R which is very in design detail like a lot of other Hondas.

F5 Dave

18th October 2011, 16:39

husaberg

18th October 2011, 16:58

Hmm, why do the left & right oil seals, which are clearly different sizes, different part numbers: - share the same description measurements?

oh well I ordered some more a few mins ago anyway before I knew the numbers.

I looked at that myself A typo as they are different the part numbers and sizes are above.out of my note book along with some old prices interesting to see how much they will have gone up.

To clearify the H100?Mb100 thing.
My take is the MB100 and H100a big fining and CDI are essentially the same bike. The Hayes manual doesn't even mention the MB100.
The S is what NZ knows as the H100 points and straight fining.But yet produced later than the MB100.
Thats my take on it.
The H100SII which I have only seen in the Hayes manual had the H100 motor in a frame with downtubes bolted on.It is ugly will post some pics.Whoops it also has CDI I didn't know that.

F5 Dave

18th October 2011, 17:07

husaberg

18th October 2011, 17:22

Through Econo Honda as that was super convenient & should be good value (never used them before) was $48 inc courier, Yeah I was expecting less too. But the big H must have heard I didn't like 'ondas & instructed I be given a special price.

Here is the prices I paid years ago Id say you did alright. $51.78 for both in other part of my diary. It would have been early 95 it was just after the last Wigram Bucket GP.
It was a bugger of a meeting for me.Magneto blew to bits (could have removed a little too much)
Left exhaust behind (Yes really)
Left Long range Tank (STD) behind Yes Really.
Lucky the old man drove the 600km round trip and delivered them for me.
Replacement flywheel someone kindly lent me touched the coils and crank seized.
Well the Mag side bearing collapsed. As a result the flywheel was hitting the stator probably the reason the original flywheel blew to bits or the result of it.
The rest of the stuff was replaces as a precaution as it was discovered the Mag bearing was a std style bearing (as in Wheel bearing.)
They don't have three oil seals do they? surely not.

Kickaha

18th October 2011, 17:45

it was just after the last Wigram Bucket GP.

First meeting I ever raced a Bucket at

husaberg

18th October 2011, 17:58

First meeting I ever raced a Bucket at

Worst meeting I ever raced a bucket at.
Remember the little Asian Dude on the RG50 he had style. Not very fast though. but total knee down and out. A case of style over substance?
I wonder who lent me the Magneto?

Kickaha

18th October 2011, 18:31

Worst meeting I ever raced a bucket at.
I got lost with all the cones:facepalm:

Remember the little Asian Dude on the RG50 he had style. Not very fast though. but total knee down and out. A case of style over substance?

Nope
I had only turned up to watch and Tony mac and Mark Butchart bullied me into doing a race

speedpro

18th October 2011, 18:48

It would have been early 95 it was just after the last Wigram Bucket GP.

I've still got the trophy, Ziffle came 2nd, even after we both crashed on the same lap.

Hilleye you need to take the Black & Decker and the cold chisel off whoever does your porting, that is seriously horrible. The hone job is a roughy as well. All my cylinder boring and honing is done by my local kart shop guys now. They may charge a bit more but everything is perfect when you get it back.

My old MB engine lasted 6 years of thrashing at all sorts of places including Manfeild, Pukekohe, Wanganui, and a few kart tracks. It made 22.5 hp when I built it and 21.8hp shortly before I blew it up. It still had the same piston and ring and sparkplug. Just for a laugh I have transplanted the sparkplug to my new engine. The rod in my Avatar is genuine Honda.

My old 19.9hp MB100 sidecar engine revved to 14,000rpm and lasted 6 years as well before a thrust washer finally nipped up. It had all original Honda parts.

I've used TKRJ and Pro-X rods and pistons as well with no complaints.

koba

18th October 2011, 20:26

Great reading here: http://en.wikipedia.org/wiki/Anorak_(slang) :Pokey:

EDI: R.E. H/MB Model details.

F5 Dave

19th October 2011, 10:39

yeah that Wigram GP wasn't the best result for me either. My poor 50 was running rough as guts all race. It finally stopped, but when I looked down the problem was the GP125 inlet rubber had split & the carb was swinging in the breeze. Think that Mike & me stayed with Tony Mac. A tradition of generosity that has continued to this day.

F5 Dave

19th October 2011, 10:41

I got lost with all the cones:facepalm:

Just say no kids,.

Hilleye

21st October 2011, 19:40

Hilleye you need to take the Black & Decker and the cold chisel off whoever does your porting, that is seriously horrible. The hone job is a roughy as well.

Blame Dangerous, it's his old bike. I just brought it like this. At this stage to be honest, it's not to much of a major because I'm just learning the basics of racing, but more power would be awesome (particularly another 8 rwhp, that's like a 50+% gain on current power) .

Bike must have made reasonable power before I got it, because it was geared so high it wouldn't pull 6th and barely pulled 5th. I doubt Dangerous would have ridden it like this, so he must have had it producing a healthy amount otherwise it would have been geared lower. It would have been geared somewhere in the vicinity of 140-150km/h when I got it. Currently it's geared for 122km/h, which it hits about 3/4 of the way down the main straight at Ruapuna.

I take it the solution is to throw that barrel away and start over with a new one ported properly. I'll find a new barrel and send it to someone to sort. Getting involved in porting is out of my depth at the moment. Actually most stuff is out of my depth, but we'll give some of it a crack.

Kickaha

21st October 2011, 20:04

Bike must have made reasonable power before I got it, because it was geared so high it wouldn't pull 6th and barely pulled 5th. I doubt Dangerous would have ridden it like this, so he must have had it producing a healthy amount otherwise it would have been geared lower.

It would rev out in top gear down the back straight at Levels when he first got it

One of the fastest Buckets at the time was DC on his MB/RS and it was roughly the same in top speed as his

dangerous

22nd October 2011, 05:54

Blame Dangerous, it's his old bike. I just brought it like this. At this stage to be honest, it's not to much of a major because I'm just learning the basics of racing, but more power would be awesome (particularly another 8 rwhp, that's like a 50+% gain on current power) .

Mike (SP) wouldent do that LOL.
Now like I have already said, yes you brought it like it is rough as engeneering HOWEVER, it was running good not the best it ever has but still very well.
Strokers can change tuning in a second its the nature of the beast. The bike was running about as powerfull as a air head 100 with std piston could, so there is obviously an issue.

I take it the solution is to throw that barrel away and start over with a new one ported properly. I'll find a new barrel and send it to someone to sort. Getting involved in porting is out of my depth at the moment. Actually most stuff is out of my depth, but we'll give some of it a crack.A good idea, it will mean welding a reed block to it ofcourse. see below for the back ground of the bike.

Bike must have made reasonable power before I got it, because it was geared so high it wouldn't pull 6th and barely pulled 5th. I doubt Dangerous would have ridden it like this, so he must have had it producing a healthy amount otherwise it would have been geared lower. It would have been geared somewhere in the vicinity of 140-150km/h when I got it. Currently it's geared for 122km/h, which it hits about 3/4 of the way down the main straight at Ruapuna. It made very good power and as above strokers can detune just in a weather change, I dont think this is the reasoning here.
Early 140's is what I remember it cranking.
The Bike was built in 1977 in a back yard in chch, the frame was replicated of a MT gp bike of that area, a CR125 was fitted and Steve Ward won many a title on it. There is a sistrer bike still with the CR in it hidden in town.
Somewere along the track it was basterised into a bucket, I asume buy a guy with the right idea but little hands on knolage. The idea was good but the workmanship crap, it did however work but was difficult to tune.
The guy I got it off and his son I dont think had any bucket racing experance and it was never raced as one IIRC.

Now Im sure it had a RG carb on it when I brought it, it sat on a heavy angle and the bole wouldent hold enough gas when wide open, so I think I got a TZR carb off yowling which sat more level and went well.
At a early stage the piston lost a corner so I bored and fitted a new piston kit. This bore may have ultered the port height slightly and was tricky to tune, I however still got a 2nd 0r 3rd in the south Is cup.
The bike slowly became harder to tune I think it was the carb but instead of replacing it I fucked about tuning it poorley... hey I was learning to aye.
Time for a freshen up and Russle thomas wasent happy with the squared bore (even tho it worked ok) so it was tidied up the only way to do this was to carve out the top and bottom I expect (ask brenchch he did the work) this proberly did ulter the port height slash timing to a point I never had its full power back but it still ran well... at this point I sold the bike to you.

It would rev out in top gear down the back straight at Levels when he first got it

One of the fastest Buckets at the time was DC on his MB/RS and it was roughly the same in top speed as hisYeh it had its moments aye, typical girl I mean stroker, sweet when on song, a right bitch other wise.

Hilleye

22nd October 2011, 10:00

I've used TKRJ and Pro-X rods and pistons as well with no complaints.

For future reference. Are there NZ agents for TKRJ and Pro-X or do you order direct online?

Henk

22nd October 2011, 10:44

R2 are agents for TKRJ and Pro X so you should be able to order through a bike shop near you.

dangerous

23rd October 2011, 15:09

For future reference. Are there NZ agents for TKRJ and Pro-X or do you order direct online?
Well this is what arsed TonyB up, KB's TKRJ suplyer, A Dorkland guy IIRC told TKRJ he wanted to be NZ's only importer and as he sold more than Tony he got his way, anyways... your MB already has a TKJR piston kit as does our old 250LC and the 350LS has a rod kit aswell, no issues with any of these items what so ever, good gear as is prox

Hilleye

23rd October 2011, 18:21

Well this is what arsed TonyB up, KB's TKRJ suplyer, A Dorkland guy IIRC told TKRJ he wanted to be NZ's only importer and as he sold more than Tony he got his way, anyways... your MB already has a TKJR piston kit as does our old 250LC and the 350LS has a rod kit aswell, no issues with any of these items what so ever, good gear as is prox

Ta for the info.

husaberg

24th October 2011, 11:25

I had a man look through the post. I can't seem to find the bit where the ignition curve came up I think it was Speedpro who said the Ignitech was only really helping at one point on his engine.
I could remember seeing these donkeys years ago.
Delay boxs, old tech piggy back to CDI units.
This company is still in business too.
It was meant at the time to be a common Mod on proddy bikes. :innocent:

I have an article bellow that explains how they work and how to basically map an old style cdi unit.

The Ignitech is the obvious top self bees knees set up, but it may be possible to provide a lower tech solution.

I seem to remember JayCar having a adjustable delay circuit.

http://http://www.jaycar.com.au/images_uploaded/LM555.PDF (http://www.jaycar.com.au/images_uploaded/LM555.PDF)
http://http://www.ehow.com/how_4827785_build-time-delay-circuit.html (http://www.ehow.com/how_4827785_build-time-delay-circuit.html)

Here is an exert off the net from a guy that builds Ignitions He mentions Buckets on his site to in regards to a Ignition he makes for the Honda 4 stroke single.

Engine revs Timing advance

1000rpm 26.0 degree
2000rpm 27.0 degree
3000rpm 25.5 degree
4000rpm 23.5 degree
5000rpm 22.0 degree
6000rpm 21.5 degree
7000rpm 20.0 degree
8000rpm 18.0 degree
9000rpm 15.5 degree
10000rpm 13.5 degree
11000rpm 11.5 degree
12000rpm 9.5 degree

"But the advance and retard goes the wrong way!?" you say. (Well one or two of you have.) I queried this with Rex, as I also thought that engines were supposed to advance the timing as the revs progressed, not retard it.
Rex replied:
"Since the early '80s much two stroke research has focused on electronics. We have seen the introduction of power valves to control the point of opening of the exhaust port. Initially this was performed by mechanical means, then designers found that to enhance the power band a control by an electric motor, itself controlled by a computer gave far more scope for power increases, especially in the midrange, just where you need to accelerate from a corner. Part of the search for midrange power focused on the ignition timing. It was found that beneath the power band created by the tuned exhaust system, more ignition advance could be given than could be tolerated at the peak horsepower rpm. A study of a MK 3 TZ350 curve will illustrate this. (Diagram to follow)
Then it was found that a further retard of the spark timing caused the exhaust pipe to run hotter, which affected the speed of the sound wave in the pipe. The net result was the pipe stayed in tune longer after peak horsepower by keeping the torque up.
We have found that retarding a fixed timing setup, by say 2-3 degrees, will give more power after peak horsepower, but there will be a drop in power on the climb up to peak horsepower. There a tailored ignition curve can give gains over the fixed timings we were used to in the early days of racing two-strokes. With limitations in engines by piston crown temperatures it pays to approach the design of the curve with care and dyno testing sometimes has to be verified with actual track testing. The same applies to other settings on the engine and the whole picture is usually a blend of art, science and experience, with failures on the way, such as holes in pistons! Hopefully this will give a brief explanation of why the general two-stroke ignition curve differs from a four-stroke curve which normally has a rise in ignition advance with a rise in rpm. Further study is recommended by reading books on the subject such as "Basic Design of Two-Strokes" by Doctor Gordon Blair and " Two-Strokes Performance Tuning" by Alexander Graham Bell."
So there you are. Years of research and hard work summed up in on or two paragraphs, supplied totally free to all of you people out there....thanks Rex.

There is also a Kiwi that makes ignitions too. Here

Hilleye

28th October 2011, 21:07

Conrod kit, check with them to see if its slotted. http://www.trademe.co.nz/motors/motorbikes/parts-for-sale/other/auction-415302675.htm

Be aware that the "Long" brand conrod kits do not come with thrust washers (just me or is this random). Original Honda thrust washers are $40 at cost, so just sent it back and ordered a TKRJ kit, which isn't necessarily a bad thing reading the comments on "Long" brand bearings.

Back up engines arrived today (big thanks to the provider). One a worked H100 in need of some TLC and the other a stock MB. Porting on the H100 gives me hope that my current MB cylinder can potentially be improved, without needing to be scraped. Will sort through properly tomorrow and maybe post some photos.

Who knows, might build another complete bike and have an engine in reserve/development (probably not though, no time).

husaberg

28th October 2011, 21:46

Be aware that the "Long" brand conrod kits do not come with thrust washers (just me or is this random). Original Honda thrust washers are $40 at cost, so just sent it back and ordered a TKRJ kit, which isn't necessarily a bad thing reading the comments on "Long" brand bearings.

Back up engines arrived today (big thanks to the provider). One a worked H100 in need of some TLC and the other a stock MB. Porting on the H100 gives me hope that my current MB cylinder can potentially be improved, without needing to be scraped. Will sort through properly tomorrow and maybe post some photos.

Who knows, might build another complete bike and have an engine in reserve/development (probably not though, no time).

I seem to have found a Eccentric pin which might work in the MB100/H100 motors that would allow the use of a Strike 52mm kart piston it alow the use of a STD style bearing as well the price looks ok.
I will post the pics and the links later.
Speedpro used this approach but the cost I guess was probably a lot more than an off the shelf mass produced solution.

http://www.lambretta-teile.de/Big-end-pin-eccentric-for-crankshaft-60-to-62mm-Vespa-PX
http://www.lambretta-teile.de/Excenter-bolt-big-end-crankshaft-2mm-stroke-Vespa-PK-PV-V50
http://www.lambretta-teile.de/Eccentric-shaft-crankshaft-52-to-54mm-Vespa-T5
http://www.vespa-lambretta-teile.com/Exzentrischer-Hubzapfen-PX-20-mm-Langhub-625-mm_1
http://www.worb5.com/shop_de_7/start.php?P_2071.php

There are other option if you bore out the crank to 22 if there is enough room.
The Bearing according to the blurbs is ment to be able to wigggle on?

I am having trouble finding the widths the Vespa seem to be around 15mm not sure with the Lambrettas where scooterboy

Hilleye

29th October 2011, 06:06

I seem to have found a Eccentric pin which might work in the MB100/H100 motors that would allow the use of a Strike 52mm kart piston it alow the use of a STD style bearing as well the price looks ok. There are other option if you bore out the crank to 22 if there is enough room.

Could you explain the advantages of doing the above for those of us that are less mechanically inclined.

speedpro

29th October 2011, 06:34

Using a good quality 52mm kart piston allows you to build a motor that works well at high revs which should equal more horsepower. The problem is that using a 52mm piston takes the capacity over the 105cc upper limit. To get around that you need to reduce the stroke which also has the added benefit of reducing peak piston velocity and acceleration given any particular engine speed so you can rev it even more. Plus they are relatively cheap and you can go to any kart shop and buy as many as you want in any size.

The 20mm pin with offset centre might be good if the big end bearing can we wiggled over the step and also depending on whether the centre section width is right for the rod + thrust washers + clearance.

Hilleye

29th October 2011, 12:44

Just got the new engine bearings today. Compared play in new bearings to play in old bearings, which I had considered flogged out and there's negligable difference.

So my next question is: The engine was definitely rattling on shutdown, but not noticably when running. Bike was spitting out of the muffler and running for a few seconds before dying again everytime we tried to start it up. What else could it be?

When pulling the engine apart I noticed that a very small part of the flywheel key had sheared off the top (vast majority was still intact), but it still wasn't able to be spun independantly by hand. Surely this isn't the problem. You can see the crank seems to show signs of flywheel turning, is this normal?

249618

TZ350

29th October 2011, 13:04

Bike was spitting out of the muffler and running for a few seconds before dying again everytime we tried to start it up. What else could it be?

When pulling the engine apart I noticed that a very small part of the flywheel key had sheared off the top (vast majority was still intact), but it still wasn't able to be spun independantly by hand. Surely this isn't the problem. You can see the crank seems to show signs of flywheel turning, is this normal?

249618

Slipped timing, in the early days we sometimes had the same problem, an overly harsh or inadvertant change down when it should have been a change up and the top part of the timing/locating key shears of inside the flywheel when the grip of the taper is unable to accelerate the flywheel enough to keep up with the crank and the timing slips, backfires can cause this too.

We have had the flywheel spin backwards so fast that it has shared the key and completely undone the crank nut and left the flywheel rattling around in the side cover. Its the quality of the fit between the tapers that joins the crank to the flywheel that matters, the key is only there to get the alignment right. If you still have the big original flywheel, get rid of it if you can and use a smaller MX one.

husaberg

29th October 2011, 13:24

Slipped timing, in the early days we have sometimes had the same problem, an overly harsh or inadvertant change down when it should have been a change up and the top part of the timing/locating key shears of inside the flywheel when the grip of the taper is unable to accelerate the flywheel enough to keep up with the crank and the timing slips, backfires can cause this too.

We have had the flywheel spin backwards so fast that it has shared the key and completely undone the crank nut and left the flywheel rattling around in the side cover. Its the quality of the fit between the tapers that joins the crank to the flywheel, the key is only there to get the alignment right. If you still have the big original flywheel, get rid of it.

Hilley

I to have suffered problems with shearing of the Key that was cured by lapping on the taper.It took me a bit of time to listen to someone to tell me that though:facepalm:

I just kept on replacing the keys making stronger ones one year it came off completely at Greymouth and someone found it and gave it too me.

I couldn't get it that the key was only there for location.
The taper is what holds it on in place.
For instance all the HP in the KTM50 is delivered though a taper with no key 10hp or so.

Henk

29th October 2011, 13:27

Valve grinding paste works well for mating the crank and flywheel.

Hilleye

29th October 2011, 14:19

Slipped timing, in the early days we sometimes had the same problem, an overly harsh or inadvertant change down when it should have been a change up and the top part of the timing/locating key shears of inside the flywheel when the grip of the taper is unable to accelerate the flywheel enough to keep up with the crank and the timing slips, backfires can cause this too.

We have had the flywheel spin backwards so fast that it has shared the key and completely undone the crank nut and left the flywheel rattling around in the side cover. Its the quality of the fit between the tapers that joins the crank to the flywheel that matters, the key is only there to get the alignment right. If you still have the big original flywheel, get rid of it if you can and use a smaller MX one.

TZ you might be onto something. I'm sure I've changed down when it should have been up, but more likely my friend may have done this during test sessions he was riding prior to BoB. So timing may have slipped, but any ideas what the rattle would have been? Like I said flywheel was still firm on the crank, flywheel nut was up tight too, mind you I'm not spinning it at 7000+ rpm when I check it. Would it be reasonable to assume that the flywheel might have been getting progressively looser or slipping further around on the crank and that's why it deterioriated gradually.

Another symptom that kind of lends itself to the above is, bike normally idles at around 4000rpm, but this had dropped to about 2000rpm just before all this happened and my rev counter (Trail Tech Vapor) started going schitzo and kept resetting (I thought it was just the battery, but changed it and it was a little better, but still kept doing it).

I can change the flywheel no problems if its a bolt on with no other mods. If I have to start modifying the ignition pickup I'm going to need some help. So with this in mind any suggestions with respect to a suitable lightweight flywheel.

husaberg

29th October 2011, 15:01

TZ you might be onto something. I'm sure I've changed down when it should have been up, but more likely my friend may have done this during test sessions he was riding prior to BoB. So timing may have slipped, but any ideas what the rattle would have been? Like I said flywheel was still firm on the crank, flywheel nut was up tight too, mind you I'm not spinning it at 7000+ rpm when I check it. Would it be reasonable to assume that the flywheel might have been getting progressively looser or slipping further around on the crank and that's why it deterioriated gradually.

Another symptom that kind of lends itself to the above is, bike normally idles at around 4000rpm, but this had dropped to about 2000rpm just before all this happened and my rev counter (Trail Tech Vapor) started going schitzo and kept resetting (I thought it was just the battery, but changed it and it was a little better, but still kept doing it).

I can change the flywheel no problems if its a bolt on with no other mods. If I have to start modifying the ignition pickup I'm going to need some help. So with this in mind any suggestions with respect to a suitable lightweight flywheel.

Just lightly file off AND I Mean Lightly
The damage and remove the key add some valve grinding paste and Spit and lap on the flywheel

Check for full contact with bearing blue and off you go.
In the box of bits. you will find a new key or 2 as well.

I would also suggest to let someone have a look in the motor before slinging it back together Yowl ling or grumph would be a good start.

TZ350

29th October 2011, 15:37

Would it be reasonable to assume that the flywheel might have been getting progressively looser or slipping further around on the crank and that's why it deterioriated gradually.

I can change the flywheel no problems if its a bolt on with no other mods. If I have to start modifying the ignition pickup I'm going to need some help. So with this in mind any suggestions with respect to a suitable lightweight flywheel.

I dont know what the rattle was, I would have to hear it to know more.

Yes the flywheel could just creep gradually, moving a bit with each miss change. Others have made lots of good suggestions about how to fix the damage and get the tapers to fit properly again.

The taper on my Suzuki GP125 is much smaller than the MB so the KX80 ignition is out but the KX125 might be worth a look as it has a bigger diameter taper.

Speedpro recently converted his, it would be worth looking at his #6 thread to find out what the doner engine was.

husaberg

29th October 2011, 17:17

I dont know what the rattle was, I would have to hear it to know more.

Yes the flywheel could just creep gradually, moving a bit with each miss change. Others have made lots of good suggestions about how to fix the damage and get the tapers to fit properly again.

The taper on my Suzuki GP125 is much smaller than the MB so the KX80 ignition is out but the KX125 might be worth a look as it has a bigger diameter taper.

Speedpro recently converted his, it would be worth looking at his #6 thread to find out what the doner engine was.

He has a MB5 one and a MB100 one spare. Plus a CR80 rotor and Stator minus the CDI unit.
I will paste him the model to look for on Ebay. I do think one step at a time with this motor he also mentioned to me it was spitting back.

Grumph

29th October 2011, 18:58

I would also suggest to let someone have a look in the motor before slinging it back together Yowl ling or grumph would be a good start.

Kind thought...but Grump is broken at present....post Greymouth.
I'm getting too old for this shit - and it was in the pits to boot.

husaberg

29th October 2011, 19:11

Kind thought...but Grump is broken at present....post Greymouth.
I'm getting too old for this shit - and it was in the pits to boot.

You should have brought sunscreen catches you CHCH people out all the time:yes:

Hilleye

29th October 2011, 19:24

I would also suggest to let someone have a look in the motor before slinging it back together Yowl ling or grumph would be a good start.

Yow Ling has already kindly volunteered to assist in the reassembly.

Hilleye

29th October 2011, 19:53

Alright so here is a picture of the existing flywheel. From what I can tell there is a superfluous plate (marked with arrow) on the outside of the main assembly that just adds weight and hence rotational inertia (not good considering what we are after) and is probably contributing to the sheered flywheel key phenomenon. Can I ditch this plate by grinding off the four marked pins/rivets without messing up the ignition?

249651

Here's a comparison between the old and a new flywheel key. Be fair to say the old one is 'munted'.

249652

F5 Dave

29th October 2011, 20:24

Oh gosh no, that's the transmorgifier. It won't run without that.

yeah those rivets just blaze off & free frizbie.

Smaller flywheel would be better still. old aircooled CR80 stator assembly bolts right on, but with an adaptor plate & a new taper cut any other mx80 will fit. just doing an RM80 one presently.

speedpro

29th October 2011, 21:34

Can I ditch this plate by grinding off the four marked pins/rivets without messing up the ignition?

249651

Don't do it. The extra plate does add mass but it also helps rigidity. I did it on the sidecar MB engine. Some time later the rivets connecting the rotor to the centre hub rattled loose. They shagged out all the rivet holes and if I recall there were a couple of cracks. Luckily it broke a wire and killed the engine before the rotor came right off. If crank inertia is a problem you are probably at the point where you need a better ignition anyway. Save your pennies and get a CRF250F generator/stator and use that to power and trigger an Ignitech. The CRF rotor bolts straight onto the MB crank like it was made for it and the mounting plate for the stator can be made from a piece of standard 14mm plate.

Hilleye

30th October 2011, 14:57

MB5 gearbox Pics of Layout that wouldn't fit above

Plus those Mad Swedes are at it again MB5 crankcase reed.
I not sure if he started before Dave or not.

http://forum.scooterforum.net/forum/f88/ronkens-honda-mt-project-153286/

Any chance you could post a better quality picture of the 6 speed transmission diagram or send a link to it?

husaberg

30th October 2011, 14:59

Any chance you could post a better quality picture of the 6 speed transmission diagram or send a link to it?

I will send it too you it should have gone with the bits anyway. I can try and post it on the MB thread I will have another go with the quality have you zeroed in on it with the plus button?

Grumph

30th October 2011, 19:44

I'm advised that a long time accumulator of MB bits is thinning the piles....Hilleye has already been offered bits and Dave will be (w)rung too.

The balance is to go on trademe.....so keep an eye out if you want engine parts.

speedpro

30th October 2011, 20:12

Not sure why you want a diagram of a 6-speed cluster for. To fit the 6-speed into a MB100 you get the whole 6-speed cluster and fit it. No mods or alterations are needed it goes straight in and makes the MB100 one of the better bucket engines - good cylinder, vey good crankshaft, and excellent gearbox.

koba

30th October 2011, 20:32

F5 Dave

30th October 2011, 20:35

Don't do it. The extra plate does add mass but it also helps rigidity. I did it on the sidecar MB engine. Some time later the rivets connecting the rotor to the centre hub rattled loose. They shagged out all the rivet holes and if I recall there were a couple of cracks. ., .

You must have got a bit unlucky there combined with the fact the sidecar did a million revs. The MB50 for example has a very similar flywheel & never came with that plate. I think your rivets must have just got shagged out on thier own accord given the situation they were in & the high loads placed on them with a sidecar wheel jumping all over the place & probably little in the way of cushioning.

husaberg

30th October 2011, 21:20

You must have got a bit unlucky there combined with the fact the sidecar did a million revs. The MB50 for example has a very similar flywheel & never came with that plate. I think your rivets must have just got shagged out on thier own accord given the situation they were in & the high loads placed on them with a sidecar wheel jumping all over the place & probably little in the way of cushioning.

When I ran The H100 original we removed a ring like that.
I am not sure if it was the H100 points one or an original MB5 one, as I had ran both.
The flywheel was lighted at the same time by a lot.
Well it was to much and it broke along the front face outside the rivets.But not because the ring was removed. I can't remember where it hapened.
On the H100 motor Hilley has it has been lightened by a lesser amount. I don't think it had the ring on it.
But you live and learn. To be honest lightening the flywheel makes it rev faster at a standstill but doesn't seem to make much difference when racing.
Hilley has a CR80 AC one that will just purchase a CDI unit from Ebay

F5 Dave

30th October 2011, 21:26

husaberg

30th October 2011, 21:33

I had a heap of MB50s over the years & none ever had the ring so must be a 100 thing. My mb50 I ran a CR80 stator & a YZ80 CDI so don't get too bogged down with compatibility. white\orange was pulsar coil & that was all you needed to know.

Interesting because I know the stator was good as I could get it to work on a XR200 unit. (well up until 6000rpm but that was 12000 for the XR unit) Try as I might
even though I checked and rechecked the wiring. I could not get it to run on a MB5 one?
Out of interest a C90 one will work if you want static timing and it wiil handle the revs as it was a lazy spark engine.

From memory the MB5 has one extra pin I think.

Hilleye

31st October 2011, 05:04

dangerous

31st October 2011, 17:53

So if I pull the one I have apart I can put it back together correctly.

Whats wrong with it? I would have to ask why pull something apart when theres nothing wrong with it?

Grumph

31st October 2011, 18:44

So if I pull the one I have apart I can put it back together correctly.

He posted that at 5.04am DD....when i first saw it shortly after post time I genuinely thought it was a question....and wondered what odds the TAB would give on it's going back correctly - all too early.

Dangerous is right Hilleye - the gearbox appears to be one of the few areas not giving problems, as it is now is how it should stay.

Buddha#81

31st October 2011, 19:29

He posted that at 5.04am DD....when i first saw it shortly after post time I genuinely thought it was a question....and wondered what odds the TAB would give on it's going back correctly - all too early.

Dangerous is right Hilleye - the gearbox appears to be one of the few areas not giving problems, as it is now is how it should stay.

........or he might be doing some preventative maint and putting new g/box brearings in it.....not giving issues now but who's to say they might be 30 years old.

Hilleye

31st October 2011, 21:34

........or he might be doing some preventative maint and putting new g/box brearings in it.....not giving issues now but who's to say they might be 30 years old.

All bearings in the crankcase are being replaced (because the case is split and I might as well while I'm at it). My intent is to not pull apart the gearbox, but if it has to come apart to change the bearings over then it's going to help if I know the sequence to put it back together correctly. You'll probably say it'll come out without being disassembled, too which I reply "Maybe it does, I don't know, but what happens if it comes apart during the process by accident."

husaberg

31st October 2011, 21:38

All bearings in the crankcase are being replaced (because the case is split and I might as well while I'm at it). My intent is to not pull apart the gearbox, but if it has to come apart to change the bearings over then it's going to help if I know the sequence to put it back together correctly. You'll probably say it'll come out without being disassembled, too which I reply "Maybe it does, I don't know, but what happens if it comes apart during the process by accident."

Digital camera and a witness to blame any mistakes on.
Personally I hate them, To hard to fix (rectify mistakes on my part) when I cock them up. I doubt anyone really likes them. (gearboxes)

F5 Dave

1st November 2011, 08:58

From having done one the day before my memory is quite clear, but they are really simple. Pull the case away & leave it in one side.

There are washers on 3 ends of the shafts. As long as you don't lose those you are pretty sweet.

Set aside some wire or a couple of big rubber bands

Best bet is to pull the shaft out that holds the sliding forks & collect those forks in your hands. The centre one has C marked on it, not sure about the others but just store them in the right order. Then pull out the gearbox complete. If it is in the left case its probably easier & there is one washer on that side. pull out the two shafts as a unit & pop those 2 washers on the other side back on. Wrap those rubber bands or wire around the ends to stop the washers getting lost or gears jumping off.

Put it back together the same way. Then slot in the shift forks & slide the shaft they live on back in, but just out of its slot. then the shift drum & slide the titties of the forks into the shift drum (may need to jiggle them up & down. Then slide the shift shaft into its hole.

easy peasy once you've done it you'll see what I mean. (heck I hope mine works now after saying that).

Gearbox bearings live in a lot of oil so are usually pretty good. Id check them & replace only if they feel grumbly. A blind bearing puller is better, but not many people have them. just got one from Torpedo 7.

koba

1st November 2011, 20:29

slide the titties... ...(may need to jiggle them up & down... Then slide the shift shaft into its hole.

Huh, sorry, were you saying something?

F5 Dave

2nd November 2011, 09:31

You must spread some Reputation around before giving it to koba again.

Don't know what yer drinking last night but yer on fire mate:lol:

dangerous

2nd November 2011, 17:54

You must spread some Reputation around before giving it to koba again.

Don't know what yer drinking last night but yer on fire mate:lol:

It's ok, I gave him the red for ya :headbang:

husaberg

2nd November 2011, 18:23

You must spread some Reputation around before giving it to koba again.

Don't know what yer drinking last night but yer on fire mate:lol:

I'm not sure that spreading anything, before giving it to Koba
enhances anyone's reputation either Dave:buggerd:

koba

2nd November 2011, 19:08

You must spread some Reputation around before giving it to koba again.

Don't know what yer drinking last night but yer on fire mate:lol:

This is me cutting down the booze for a bit, I'm not sure its a good idea...

It's ok, I gave him the red for ya :headbang:

I hope you aren't talking about pubes!

I'm not sure that spreading anything, before giving it to Koba
enhances anyone's reputation either Dave:buggerd:

Now, what is it you drink? :killingme

husaberg

2nd November 2011, 20:17

This is me.... sure its a good idea...

Now, what is it you drink? :killingme

Beer only.
I leave the "cock-tales" to the Northerners :sick:

Henk

2nd November 2011, 20:44

Apparently I can't spread anything to Koba for a while either.

husaberg

2nd November 2011, 21:22

Apparently I can't spread anything to Koba for a while either.
I was actually slinging shit at Dave. Last one I promise
It is not fair to cast any blame on Koba's. He's just making the best, Of a Bad "Ass" situation.

husaberg

16th November 2011, 19:56

So Hilley what is the progress with the motors?

dangerous

16th November 2011, 20:24

So Hilley what is the progress with the motors?
its fucked, thanks to the privious owner... mind you it did get him a 2nd in the south Is cup, so it couldent a been to bad :cool:

husaberg

16th November 2011, 21:09

its fucked, thanks to the privious owner... mind you it did get him a 2nd in the south Is cup, so it couldent a been to bad :cool:
Which previous owner I sold him a couple too.
mind you mine were a little prettier in the porting.:rolleyes:

Did it spit back with you I am guessing you shortened the piston?:spanking:

dangerous

17th November 2011, 04:49

Did it spit back with you I am guessing you shortened the piston?:spanking:
no and no, its a standard TKJR mb piston

Hilleye

17th November 2011, 19:39

Ok, so apologies for not giving updates but duty calls and been out of touch. So here's the plan.

After inspection there's actually not much wrong with the original motor, less the fact the flywheel slipped on the crank and fucked up all the ignition timing (porting isn't great but that's another issue). All the bearings etc being flogged out turned out to be a false alarm when compared to new ones. Flywheel is being lightened to try and prevent a reoccurance. Taper has been tidied up but still has some quite deep score marks so could probably do with remachining (volunteers?). Flywheel has some metal its picked up from the crank 'welded' to the inside of the taper that needs to be skimmed out. Other option is to use retaining compound in lieu of tidying up jobs on the crank and flywheel tapers. Anyway it will be put back together pretty much as is to get me back on the track and racing.

250846250845250847

Second MB engine will get the full development treatment in slow time. First stage is to replace all the big end and bearings and switch over the 6 speed gearbox from the H100 Husaberg gave me. Second stage will be to throw on a CR80 flywheel and ignition, which is also now sitting in the garage. Third stage will be send the barrel away for a porting job, which is beyond my ability particularly when I read things like ESE thread on transfer port angles and the like. Final stage will be to get an exhaust made up to suit the porting (assuming the current one is no good).

speedpro

17th November 2011, 21:59

I've seen MB cranks like this before. I just filed off the high spot where it had picked up and put it back together with Loctite bearing mount. I never had a problem on a 14,000rpm engine with it ever coming loose again.

dangerous

17th November 2011, 22:00

After inspection there's actually not much wrong with the original motor, less the fact the flywheel slipped on the crank and fucked up all the ignition timing
I KNEW IT :msn-wink:

husaberg

17th November 2011, 22:39

I KNEW IT :msn-wink:

lap it on with fine grinding paste please.

Hilleye

18th November 2011, 18:44

speedpro

18th November 2011, 18:55

You've got rid of the balancing adjustments.

Henk

18th November 2011, 19:08

I've just put some weight back on my flywheel in the hope it helps me get better starts.

F5 Dave

18th November 2011, 21:19

Well at least he knows where to redrill some to get a bit closer.

Just chuck the CR one on.

husaberg

18th November 2011, 21:48

Alright, here are the before and after shots of the flywheel. Have removed the metal ring that seems totally surplus to requirements and skimmed about 2mm off the outer thickness. Hoping that the reduction in reciprocating mass will aid the aid the taper in supporting sudden engine speed changes. If anyone can give me a steer on how to get the remnants of the rivets out I'd be much obliged, it'll save them exiting of their own accord at 10k rpm. Tried punching and pressing, no joy but that was before we removed the ring. Drilling them out has been suggested.

250883250885

Hilley for reference can you have a look at the one on the old bucket H100 motor.
There may be a hint there.
Post a pic if you want. It will be a little rusty but there may be a reason for the odd machining on it?

Please please lap in on with grinding paste. Then check the fit with bearing blue. After this is done it will never again give trouble. (Assuming its not totally f...ed)

Or has Dave said put on the smaller lighter one. But the flywheel weight is not a major difference while racing.

Hilleye

19th November 2011, 07:04

We checked the balance of the flywheel before machining, it wasn't great. Nothing else seems to be, why should the flywheel be any different right. For some reason the exterior turned out to have a slight eliptical shape, which I found out when machining it on the lathe, anyway at least its an actual circle now. Anyione else found this phenomenon on an MB flywheel? Thickness is now uniform all the way round the circumference and balance now appears to be better. Time will tell. Worse comes to worst I have two other MB flywheels to fall back on.

husaberg

19th November 2011, 07:22

We checked the balance of the flywheel before machining, it wasn't great. Nothing else seems to be, why should the flywheel be any different right. For some reason the exterior turned out to have a slight eliptical shape, which I found out when machining it on the lathe, anyway at least its an actual circle now. Anyione else found this phenomenon on an MB flywheel? Thickness is now uniform all the way round the circumference and balance now appears to be better. Time will tell. Worst comes to worst I have two other MB flywheels to fall back on.

One of them was already lightened to.:confused:

Hilleye

20th November 2011, 12:29

husaberg

20th November 2011, 12:40

Well, threw the motor back together quickly to see if it would run after sorting the flywheel free wheeling on the crank issue. Seems I definitely got the flywheel mating to the crank shaft taper sorted, no way is it coming off without a flywheel puller. Alas now no spark, so no running, so no racing today.

Bike turns over when pushed, with no rattles or any other symptoms of anything untoward happening, except it fails to spring into life as hoped.
What do the stators coils look like now i guess the flywheel was hitting them.

Also my experience with ignitions Is it is nearly always the dud connections or earthing and a lot of the time it is a kill switch issue. My 2 cents.
assuming it was running prior that is.

Hilleye

20th November 2011, 18:03

What do the stators coils look like now i guess the flywheel was hitting them.

Also my experience with ignitions Is it is nearly always the dud connections or earthing and a lot of the time it is a kill switch issue. My 2 cents.
assuming it was running prior that is.

Once i get the flywheel off again I'll show you what the stator coils look like. Waiting for my flywheel puller to be given back.

Bike has two kill switches in series. One for ordinary shut down, which is essentially brand new and the other 'pull out' one required for street racing, which was on the bike when I got it. Shouldn't be two hard to test continuity of the circuit through them as they're both always 'on' unless pushed or pulled. Will need help with anything more complicated than that.

Hilleye

20th November 2011, 20:03

husaberg

20th November 2011, 20:35

After thinking on things a bit and looking at some other H100 and CR80 ignitions seems like the little pickup for the CDI might have been a casualty of the rogue flywheel and this might be the reason for the lack of spark. Will confirm once I can get the flywheels off both the MB motors to conduct a direct comparison. Couple of you actually highlighted this as a potential issue way back after I identified the flywheel rotating on the crankshaft so kudos to you guys.

Here's a picture of the ignition before I placed the flywheel on. Bracket was centrally positioned in the slots (third bolt has been left out for the picture to allow viewers to see relative position), wondering what the likely impact of rotating clockwise or anticlockwise would be (obviously it'll advance or retard the ignition, but what impact will this likely have on engine power and delivery).

250997

Can any of you identify from the picture whether the pick up has been munted?

is the steel sticky out bit still sticking out a bit. You can't see it in the pic because it is looking straight on.
The ignition windings looks like it has got hot before. Have you got a multimeter if you have test the there is the figures in the manual. in fact the manual has a good check list in it.

the ignition timing std is around 15 odd degrees i think (check the Manual). If you advance the timing so it fires a greater distance before TDC it may run a little better esp down low if you retard the timing it may rev a little better right up top. It may also over heat in either direction if you overdo it.
All engines like different timing depending on tune it is a bit of trail and error. Be warned get in someone real experianced before attempting to play much with the timing to much and get used to checking the plug and lifting the head regularly too.
Most ruined engines are a result of over advanced ignition chasing that elusive crisp edge. same with jetting some people like to live dangerously.

koba

21st November 2011, 05:51

husaberg

21st November 2011, 15:31

The changes husaberg mentions don't need much either.
A change of minutes (as in fraction of a degree) can sometimes make a noticeable difference.
Other times it may take a couple of degrees to make any noticeable difference.
If it is waay out and still runs it is going to be bad.

Looking at the pic closely it appears DD may have slotted the the stator to allow for a greater range of timing changes.
Maybe he could enlighten you to what initial advance he ran.
In fact he could give you full account of the mods comp etc.

Kickaha

21st November 2011, 15:36

Maybe he could enlighten you to what initial advance he ran.
In fact he could give you full account of the mods comp etc.

Fuck you're a funny man:killingme he'd be lucky if he knew what day it was

husaberg

21st November 2011, 17:28

Looking at the pic closely it appears DD may have slotted the the stator to allow for a greater range of timing changes.
Maybe he could enlighten you to what initial advance he ran.
In fact he could give you full account of the mods comp etc.

Fuck you're a funny man:killingme he'd be lucky if he knew what day it was

In fairness to me I did say maybe and could.:shifty:

Hilleye

21st November 2011, 17:31

Pretty sure those plates come slotted.

husaberg

21st November 2011, 17:39

Pretty sure those plates come slotted.

Yes but looking at the slots they do not look even. The holes have a "chainsaw file" look to them. It could be a the angle of the camera.

F5 Dave

22nd November 2011, 09:00

well it doesn't locate on the holes so no harm. Always best to rotate the plate anticlockwise & work from the most retarded position as a starting point.

husaberg

22nd November 2011, 19:05

& work from the most retarded position as a starting point.

Yes as Dave mentions it does not locate on the slots. But it does allow for a more potentially dangerous level of timing adjustments which it what i was trying to point out. With the std slots it is pretty hard to do any damage tinkering.
BTW Dave it is Time you got more PC.
I think you are "Special" .

I must admit it sounds kind of right "Special Dave":innocent:

I just realised in hindsight some people way take umberance to this comparison I made in jest. I would like to apologize to any one who is differently abled or know or loves some who is for any comparisons I may have made to Dave.

Henk

22nd November 2011, 19:51

Tempted to get some "special Dave fan club" shirts made :)

speedpro

22nd November 2011, 21:09

Tempted to get some "special Dave fan club" shirts made :)

I'd buy at least one

F5 Dave

23rd November 2011, 08:07

husaberg

23rd November 2011, 15:45

You'd need to, they'd slip off you no-shoulders.

Actually with any tuning you are going to have to stray from std in many cases to be safe. Delayed ignition is always safer & if you spin the engine to higher revs then more often a Delayed position is the right one & std could be over advanced. . . .Something Husaberg has never been accused of.:bleh:

Husaberg has never (yet) suffered from premature ignition........ :scratch:

So how many "Special Dave" fanclub T shirts Should i put you down for, Dave. The initial run of 10 looks to be almost sold out.

I hope you don't mind me a"borrowing" your likeness. Not many blokes could pull that outfit off. But you sure work it.:killingme

Hilleye

25th November 2011, 10:58

Bike has two kill switches in series. One for ordinary shut down, which is essentially brand new and the other 'pull out' one required for street racing, which was on the bike when I got it. Shouldn't be two hard to test continuity of the circuit through them as they're both always 'on' unless pushed or pulled. Will need help with anything more complicated than that.

Correction to this. As Yow-Ling pointed out to me the switches are normally 'open' and kill the ignition when 'closed'. With this in mind the kill switches are wired so that if either is 'closed', the ignition dies, so probably in parallel, not series as previously mentioned.

husaberg

25th November 2011, 15:34

Correction to this. As Yow-Ling pointed out to me the switches are normally 'open' and kill the ignition when 'closed'. With this in mind the kill switches are wired so that if either is 'closed', the ignition dies, so probably in parallel, not series as previously mentioned.

I was just adding it from experience from ignition problems from Pattern XR button style ones and others experience as few people think to check them. looking at your pics and because of your other troubles. I would suspect the stator to be your trouble, but it pays to check them anyway. Yes they just ground the ignition so are in parallel. Not sure about the lanyard ones though. Introduced after I finished.

Hilleye

29th December 2011, 19:35

Right here is a copy of the TZR race kit Manual for the carb.

It does say as I alluded too earlier to block it off, but has anyone confirmed that the fueling is wrong on the bike as it is now? If the fueling is ok now, I can't see how it will gain any HP unless the fueling is crap at the moment. I should probably point out this was for this model carb whatever it is and no doubt the Crafty Japanese made a few changes during the model run.

Maybe Hilly should give us a run-down of the carb jet specs as they are now.

253943253944253945

Right was rereading this as one is inclined to. Here's the info requested, carb is a Mikuni 1KT (basically same carb as you gave me Hus, remote choke seems to be only difference) running a 350 main jet, which I think is way too big (but the dyno doesn't lie, this one had the best fuel air mix and most power). So I'd say that the carb isn't fuelling very well.

Essentially what I can tell from the diagrams is that the air jet can either be fed from the plastic tube located at the side or from the opening in the bellmouth. I've now blocked the plastic tube and opened the bellmouth air jet, but haven't drilled it out to 2.5mm in accordance with the F3 racer instructions yet.

I'm not to familiar with power jets or how they work, but understand what they're designed to achieve. So with this in mind I have a couple of questions. Is the power jet with the setup shown likely to work on the MB100 or is it just going to be further complicating the carb fueling and making jetting it correctly difficult? Do I actually need a power jet or is the carb likely to be able to cope without one?

Lastly, was looking at trying to set the float level correctly and the current set up has the carb on about a 5-10 degree angle. Is there a trick to this or do I need a brand new CNC machined inlet manifold that puts it at the correct angle? I believe this is potentially contributing to what I think is the emptying of the float bowl in parts of the track (not the straight, its after coming out of the infield twisties, bike just drops right off until its stood up right and fuel seems to start flowing again). Photos to follow.

husaberg

29th December 2011, 20:05

253943253944253945

Right was rereading this as one is inclined to. Here's the info requested, carb is a Mikuni 1KT (basically same carb as you gave me Hus, remote choke seems to be only difference) running a 350 main jet, which I think is way too big (but the dyno doesn't lie, this one had the best fuel air mix and most power). So I'd say that the carb isn't fuelling very well.

Essentially what I can tell from the diagrams is that the air jet can either be fed from the plastic tube located at the side or from the opening in the bellmouth. I've now blocked the plastic tube and opened the bellmouth air jet, but haven't drilled it out to 2.5mm in accordance with the F3 racer instructions yet.

I'm not to familiar with power jets or how they work, but understand what they're designed to achieve. So with this in mind I have a couple of questions. Is the power jet with the setup shown likely to work on the MB100 or is it just going to be further complicating the carb fueling and making jetting it correctly difficult? Do I actually need a power jet or is the carb likely to be able to cope without one?

Lastly, was looking at trying to set the float level correctly and the current set up has the carb on about a 5-10 degree angle. Is there a trick to this or do I need a brand new CNC machined inlet manifold that puts it at the correct angle? I believe this is potentially contributing to what I think is the emptying of the float bowl in parts of the track (not the straight, its after coming out of the infield twisties, bike just drops right off until its stood up right and fuel seems to start flowing again). Photos to follow.

You read to much. HA HA

I would try it with the inlet manifold you got from me the chopped and re drilled RD250 one for a start it sets it on the std factory angle secondly put a foam pod filter and see if you still encounter fueling issues. PS make sure the oil feed at the top of the carb is blocked.

Float height is in the manual i posted a link for.

The choke in the carb you got of me is actually a std mb5 part it just happened to fit. Second thought put my choke in your carb as well as this might help!

Check the fuel line for flow not sure what tank you run but check it. if the orifice or the fuel line is blocked or to small it will be a defacto mainjet. Also check the breather on the fuel tank often over looked.

I never ran over a 250 main jet with the PJ in place.

The powerjet in the TZR carb is an odd position. But don't panic the PJ and the main jet together will add up to what the MJ should but if you disable it .I wonder if it is in fact disabled.

If you want to disable it go back to Dave and speedpros bits above.

I hope this helps.

just had a small look on thread but the manual is online i have a copy somewhere if you can't find it pm your email and i will email you the parts of the manual or the link or i will post it for you.

Hilleye

30th December 2011, 17:43

The MB lives again.

Yow Ling

30th December 2011, 20:03

good work nik, racing on the 7th and 8th $70 for the weekend and then the weekend after with Cams

Hilleye

8th January 2012, 09:32

Anyone got the number of a Christchurch based M/C wrecker? Spoke to Don at Pitlane he says he sold all his stock to Simon Wooding, but doesn't have any contact details for him.

End of the clutch cable came off yesterday (one of many things that went wrong, but we persevere for the time being. Least the bike had the decency to break down close to the pits).

Also spoke to Don about soldering the end back on the cable, he reckons unlikely to be successful particularly with an old cable, anyone else had any dramas with this? Can anyone tell me were I should go to get cable internals made?

Kickaha

8th January 2012, 09:42

Can anyone tell me were I should go to get cable internals made?

Most likely somewhere like Safe r brakes could do it or budget motorcycles used to have a stock of aftermarket suff you might be able to match something up

speedpro

8th January 2012, 19:33

Kart shops typically have a stock of cable making stuff

Hilleye

8th January 2012, 21:00

Thanks to all those who offered advice on where to go for the clutch cable. Big thanks to Yow Ling for all his help this weekend, definitely some beers owed to you.

Anyway so the bike still has a few gremlins, but I aim to shoot them one at a time as they show themselves. At the moment one is proving elusive, I'm certain its a fueling issue, but can't quite sort it.

Symptoms are after coming out of any sort of extended period lent over, particularly to the right hand side, about 100 - 200m further down the track the bikes power dies right off. By this I mean that the only thing keeping it running is the momentum of the bike, if I pulled the clutch in the motor would stall. It stays this way for what seems like 2 - 3 secs then clears and the bike is off again. At Ruapuna it's doing this after the long right hander out of the in field, which hits coming out of the right hander that follows it before the lefts that lead into the dipper. It's also doing it after the dipper and is hitting right as you go into the sweeper. It has only done this since the bike was dyno tuned and a bigger main jet was installed (no other changes were made).

Originally I thought it was a supply problem, but now I'm not so convinced. I did find a fuel filter that was restricting flow, but this was replaced and the problem persists. I've tried numerous fuel line configurations (some are shown) on the track none of which seem to clear the problem. I've checked flow with the bike lent right over on both sides and there seems to be no issue with it making it as far as the carb. I've checked the float height, but did this with the carb level (from the pictures you can see it's slightly canted fwd on the bike) should I be setting this level with it sitting on the bike?

254753
Original fuel line configuration.

254757254758
Configuration used this weekend. No improvement.

254756254752
Possible fuel filter header tank to rule out any possibility of supply issue.

I seem to be spending a lot more time working on the bike rather than riding it, which is not really what I'm after. The aim was to become a better rider not better mechanic by taking up racing. Although the latter is not unwelcome, missing four out of five track sessions this weekend with bike malfunctions was frustrating.

F5 Dave

9th January 2012, 09:28

Hmm, well I know what the problem is, but didn't we cover this before? Can't be bothered looking back 14 pages. either way I had this problem on my H when confronted with a long track like Ruapuna. Your carb is on more of an angle than mine.

So I found that these carbs can suffer from not refilling fast enough. My bodge was to fit an extender on the main jet to get it to reach the bottom of the float bowl. That fixed the issue. I soldered on a brass extension made from an old connector, but anything glued on may work. Did alter the jetting slightly.

I'd drilled out the float valve but it didn't help.

But on another carb I found the problem was the horizontal passageway feeding the float valve. I drilled out the brass ball & the passage way & then glued a stopper in the outside hole I'd made & job jobbed.

Hilleye

9th January 2012, 18:51

Hmm, well I know what the problem is, but didn't we cover this before? Can't be bothered looking back 14 pages.

No one went in to much detail. Probably because there were a number of other issues presenting simultaneously.

So I found that these carbs can suffer from not refilling fast enough. My bodge was to fit an extender on the main jet to get it to reach the bottom of the float bowl. That fixed the issue. I soldered on a brass extension made from an old connector, but anything glued on may work. Did alter the jetting slightly.

Do you think a length of fuel hose stuck over the main jet extending down to the bottom of the float bowl to act as a syphon might work?

Grumph

9th January 2012, 19:10

[QUOTE=Hilleye;1130230943

Do you think a length of fuel hose stuck over the main jet extending down to the bottom of the float bowl to act as a syphon might work?[/QUOTE]

NO - you need to increase fuel flow into the bowl - get Mike to drill out the passages as has been suggested - or just run more fuel in the bloody tank.....

sidwyz

9th January 2012, 20:38

Symptoms are after coming out of any sort of extended period lent over, particularly to the right hand side, about 100 - 200m further down the track the bikes power dies right off. By this I mean that the only thing keeping it running is the momentum of the bike, if I pulled the clutch in the motor would stall. It stays this way for what seems like 2 - 3 secs then clears and the bike is off again. At Ruapuna it's doing this after the long right hander out of the in field, which hits coming out of the right hander that follows it before the lefts that lead into the dipper. It's also doing it after the dipper and is hitting right as you go into the sweeper. It has only done this since the bike was dyno tuned and a bigger main jet was installed (no other changes were made).

I had problems with fuel supply but only at Taupo, my bike would do a lap or two then starve of fuel, miss fart and die.

I thought it may have been because I was lent over for a lot longer with minumum fuel in the tank and wide open throttle for so long down the straight and not enough time to fill the bowl, so put heaps in, still did it.

After looking at everything it was suggested to me maybe I was getting a fuel lock in the tank,
The next race I undid the fuel cap evertime I was going down the straight.

All of a sudden the problem was gone, I now have another fuel cap with a vent for taupo.
Worth a look.

speedpro

9th January 2012, 20:47

Leaning will have nothing to do with it. Force on a bike is always more or less through the centre ine of the bike to the contact patch of the tyres. If it isn't then you are about to or have just crashed.

I like the suggestion above, having suffered the exact same problem myself.

Hilleye

9th January 2012, 21:50

NO - you need to increase fuel flow into the bowl - get Mike to drill out the passages as has been suggested - or just run more fuel in the bloody tank.....

Grumph, I've brimmed the tank and it still happens.

I have now drilled out the passages. Fuel passage taken from approx 3.5mm to 4.0mm (30% increase in flow area if my maths are right). Float valve taken from 2.5mm to 3.0mm (44% increase in flow area), could possibly go bigger, because this is the limiting factor now, if someone could tell me what the max size it can be and still seal properly. Float valve was about 3.4mm - 3.5mm across so was reluctant to open it up anymore. Opted for the conservative approach to begin with will try it on the track and see how it goes before going crazy.

I had problems with fuel supply but only at Taupo, my bike would do a lap or two then starve of fuel, miss fart and die.

I thought it may have been because I was lent over for a lot longer with minumum fuel in the tank and wide open throttle for so long down the straight and not enough time to fill the bowl, so put heaps in, still did it. After looking at everything it was suggested to me maybe I was getting a fuel lock in the tank, the next race I undid the fuel cap evertime I was going down the straight. All of a sudden the problem was gone, I now have another fuel cap with a vent for taupo. Worth a look.

The tank is vented, but I had thought maybe I was getting a fuel lock in the tank so I did check it. Filled the tank to the brim and drained through the fuel line to see if there was any interuptions with supply. There wasn't any problems at rest, but that doesn't mean that it couldn't be happening whilst on the track, so I'll check it out. I might have to increase the size of the existing vent hole in the cap, it may be insufficient or getting covered as the bike is lent over and it may be enough to create the fuel lock. Unlikely though due to the nature of the force acting on the fuel in the tank during cornering which should be trying to push it towards the lowest point in the tank (i.e the outlet pipe).

You don't think it's weird that it always happens in the same places on the track though?

husaberg

9th January 2012, 21:59

Grump, I've brimmed the tank and it still happens.

I have now drilled out the passages. Fuel passage taken from approx 3.5mm to 4.0mm (30% increase in flow area if my maths are right). Float valve taken from 2.5mm to 3.0mm (44% increase in flow area), could possibly go bigger, because this is the limiting factor now, if someone could tell me what the max size it can be and still seal properly. Float valve was about 3.4mm - 3.5mm across so was reluctant to open it up anymore. Opted for the conservative approach to begin with will try it on the track and see how it goes before going crazy.

The tank is vented, but I had thought maybe I was getting a fuel lock in the tank so I did check it. Filled the tank to the brim and drained through the fuel line to see if there was any interuptions with supply. There wasn't any problems at rest, but that doesn't mean that it couldn't be happening whilst on the track, so I'll check it out.

You don't think it's weird that it always happens in the same places on the track though?

Some real simple maths here how many hp did a TZR250 have well i guess it is a lot more than 2x the the output of this bike.

Std the TZRs have quite a large inlet pipe on the carb.Thus the fuel pipe way larger than the normal VM Mikuni.

Your tank has a very low outlet so i would dummy up another tank a take a couple of laps and see what happens.

I would also put an foam air filter on it.

The other thing is are any of the fuel lines hard?
Looking on the last page i am unsure why the routing of the fuel line is not directly from the tap to the inlet of the carb even if you have to do a hard bend or put in a brass bend i think it would be better than the two you have tried.

Last one can you try the inlet manifold of mine from the box . The the modded rd250 one. Although it does look a bit like your engine may be on more of an angle than it would be on in the std chassis.

Hilleye

9th January 2012, 22:48

Some real simple maths here how many hp did a TZR250 have well i guess it is a lot more than 2x the the output of this bike.

Agreed, but they only run a 210 main jet. This bike is running a 350 (lets not get into whether it should or not, dyno says it should so it does, otherwise it runs so lean it'll seize). Remember the bike fueled fine before the increase in jet size and it was running a 260 main jet then.

Std the TZRs have quite a large inlet pipe on the carb. Thus the fuel pipe way larger than the normal VM Mikuni.

Yup, roughly something in the vicinity of 3.5mm in diameter.

Your tank has a very low outlet so i would dummy up another tank a take a couple of laps and see what happens. .

Low outlet is true, but tank still sits high enough to generate good fuel pressure. If the problem persists this will be my next option to try and sort it.

The other thing is are any of the fuel lines hard?

Fuel lines are all brand new. As is fuel filter.

Looking on the last page i am unsure why the routing of the fuel line is not directly from the tap to the inlet of the carb even if you have to do a hard bend or put in a brass bend i think it would be better than the two you have tried.

Although I haven't shown it I've also previously routed the fuel line as you have described (and with just the tap and no fuel filter). Problem is still there, weirdly if anything the more direct the routing the worse the problem seems to be on the track (could be my imagination though).

A right angle bend coming off the fuel outlet from the tank and one to get a better angle into the carb inlet might be beneficial so I'll look at these as well to try and keep the entire fuel line above the level of the carb inlet.

husaberg

10th January 2012, 06:09

Agreed, but they only run a 210 main jet. This bike is running a 350 (lets not get into whether it should or not, dyno says it should so it does, otherwise it runs so lean it'll seize). Remember the bike fueled fine before the increase in jet size and it was running a 260 main jet then.

Low outlet is true, but tank still sits high enough to generate good fuel pressure. If the problem persists this will be my next option to try and sort it.

Although I haven't shown it I've also previously routed the fuel line as you have described (and with just the tap and no fuel filter). Problem is still there, weirdly if anything the more direct the routing the worse the problem seems to be on the track (could be my imagination though).

A right angle bend coming off the fuel outlet from the tank and one to get a better angle into the carb inlet might be beneficial so I'll look at these as well to try and keep the entire fuel line above the level of the carb inlet.

Wait a min

Are you saying there was no problem until you upped the main jet?
PS you will get away with a smaller main with an air filter
next yes one fuel pressure varies according to height the variance is about 1.42 psi/meter fuel in tanks slosh around though.

F5 Dave

10th January 2012, 08:45

Hilleye

10th January 2012, 14:20

Wait a min, are you saying there was no problem until you upped the main jet?

Yup, that's exactly what I'm saying.

So it was a TZR carb with power jet? Think so. Same body carb w/o pj is what my H ran, off a KR250. Ran the button type jets rather than the longer hex jets. They didn't extend down into the float very far, hence the extn.

It's the TZR carb with the power jet. Running the longer hex type jet.

speedpro

10th January 2012, 17:23

Take the float bowl off, connect the fuel line, hold an ice cream container under the carb, turn on the fuel tap. I'd be very surprised if it flows less than the motor could possibly use in your wildest dreams. I've got a 430 main in my bike which has been fitted on the dyno. No other mods have been made to the carb.

husaberg

10th January 2012, 17:55

I think with the passages increased as you have should nail it. Float will need to be reset so it doesn't flood as it will sit further in of course.

btw TZR250 1KT =45hp, or 22.5 per cyl. This only takes a airfilter-less less efficient engine to make this borderline.

So it was a TZR carb with power jet? Think so. Same body carb w/o pj is what my H ran. Off KR250. Ran the button type jets rather than the longer hex jets. They didn't extend down into the float very far, hence the extn. Fuel line on the jet won't seal enough to be used as a straw & could slip causing a starvation. I'd try it as is & also make an extension jet to jam in if you still have issues.

btw mine always used to run out a bit before the right hander after the hairpin at 'puna, sometimes exiting the hairpin.

Dave Hillies engine made 14hp yes 14 hp

The stock tzr carbs can flow more than enough petrol to handle considerably more power than 22.5 they are not even close to borderline.
this engine seems to a have a list of problems.
Was it raced sucessfully and did it seize before it was put on the dyno to sort out the fueling.
A while back i posted some mods for the tzr the race kit mods.
what does the plug look like as well.

Hilleye

10th January 2012, 19:31

Hillies engine made 14hp yes 14 hp. The stock tzr carbs can flow more than enough petrol to handle considerably more power than 22.5 they are not even close to borderline. What does the plug look like as well.

I agree the MB isn't making anywhere near what a TZR makes, but the MJ size it's running is a lot bigger, which indicates it's a lot less efficient than a TZR. Maybe we should consider what the carb is trying to flow, which seems to be a bit more than a standard or even race TZR (which runs a 250 MJ) not just how much power it's making.

This engine seems to a have a list of problems. Was it raced sucessfully and did it seize before it was put on the dyno to sort out the fueling.

It would appear the reason it seized was because it was probably running a critically lean fuel mix, so it wasn't having any of the fuelling issues because the MJ was smaller. The problems are being resolved slowly, I believe I'm down to the fueling issue and the bike should be on song (albeit a rather peaky gutless song at present).

A while back i posted some mods for the tzr the race kit mods. What does the plug look like as well?

I'd show you the plug, but the bike wasn't running properly for long enough last weekend for it to mean anything. I'm working through the proddie racer mods on the other carb and will chuck it on next time I'm at the dyno to see if it makes a difference. You'll also be pleased to hear a pod filter is on order and should arrive by the end of the week.

254880254877

Here's a picture of the petrol cap. The positioning of the venting holes (red circles) is just stupid, they're outside the the tank seal, so the tank is venting atmosphere to atmosphere, which obviously achieves very little. I assumed there was one in the centre as well, but compressed air comfirmed there wasn't (there is now though and the other ones will be sealed up to prevent the fuel just washing out on to the top of the tank). However even without the new vent there was still seepage of fuel mix from under the tank cap to top of the tank, so I doubt it's airtight which is why I don't see any fuel locking when draining the tank from full at rest. It seals better than when I first got it though, the top of the tank was slick with fuel mix after a race, ridiculous.

gav

10th January 2012, 20:20

Is a Keihen carb off an NSR250 worth trying? They are angled so the float bowl sits in more level.

254888 254889

husaberg

10th January 2012, 20:42

I agree the MB isn't making anywhere near what a TZR makes, but the MJ size it's running is a lot bigger, which indicates it's a lot less efficient than a TZR. Maybe we should consider what the carb is trying to flow, which seems to be a bit more than a standard or even race TZR (which runs a 250 MJ) not just how much power it's making.

The mainjet will need to be bigger than a std TZR not because of power but because as it is it runs without a filter.

It would appear the reason it seized was because it was probably running a critically lean fuel mix, so it wasn't having any of the fuelling issues because the MJ was smaller. The problems are being resolved slowly, I believe I'm down to the fueling issue and the bike should be on song (albeit a rather peaky gutless song at present).

Some of the other reason i think it runs not right are as a result of an odd pipe overly long inlet manifold and err... unknown porting no offense to its creator intended.
here is the link to a race kit jetting mods not that i think it needs them.
http://edj.net/2stroke/tzr/racingmanual/
http://www.classicyams.com/technology/technology/yamaha-tzr250-tuning-2ma-1kt.html

are you able to put in the other reed valve and manifold.
I just reread your last post is the powerjet std ie not blocked have you tried running the bike without a mainjet to see where the fueling issue is?

254892254895254896254897

Hilleye

10th January 2012, 20:49

However even without the new vent there was still seepage of fuel mix from under the tank cap to top of the tank, so I doubt it's airtight which is why I don't see any fuel locking when draining the tank from full at rest. It seals better than when I first got it though, the top of the tank was slick with fuel mix after a race, ridiculous.

I stand corrected. There is actually quite a good seal with the cap and the tank can be negatively pressurised to well over a complete atmosphere (positively pressurised not anywhere near as much, barely 0.2 bar, which is possibly why a little seepage occurs when it sloshes against the cap under braking or the like, but no air can get in). Unsure why this possible fuel locking didn't present itself at rest when allowing the tank to just drain out. Opening the cap didn't increase flow speed during these tests either. Fixed now anyway, tank is now properly vented and another possible cause is eliminated.

Fuel will flow from the tank like the water over Niagara Falls. The carb can now flow Niagara Falls type volume with the enlarged fuel passages. Things are looking up.

koba

10th January 2012, 21:05

The mainjet will need to be bigger than a std TZR not because of power but because as it is it runs without a filter.

All the talk of main-jet sizing, esp vs horsepower sounds like a load of rot. Do remember all sorts of variables change, such as how hard the jet is being sucked at a given time in a given motor. I'd also take a guess and say the emulsion characteristics are likely to change too.

When I had my MB100 almost standard except for the pipe any bigger than the std main-jet size would be four-stroking with richness. The power had definitely increased and with it the fuel required. It was passing it all through the same size jet.

husaberg

10th January 2012, 21:59

All the talk of main-jet sizing, esp vs horsepower sounds like a load of rot. Do remember all sorts of variables change, such as how hard the jet is being sucked at a given time in a given motor. I'd also take a guess and say the emulsion characteristics are likely to change too.

When I had my MB100 almost standard except for the pipe any bigger than the std main-jet size would be four-stroking with richness. The power had definitely increased and with it the fuel required. It was passing it all through the same size jet.
Agreed I believe i gave my H100/tzr250 carb settings about 10 pages ago.
but as a rule it is silly to suggest adding a filter will do anything but richen the fueling.

Just as ripping of a air-filter and air box would not lean out the mixture complicate the mid-range as well.
i was comparing the fueling in relation to the std TZR spec.
but yes engines are all different tuning on the web is nearly impossible.
Carbs are quite forgiving in most respects.
Mine was never a problem with surprisingly near std TZR specs.
Also as you say up to a point carbs will auto enrichen with increased airflow it is in their nature up to a point .

Me harping about the filter is about the fact that Canterbury in the summer is a bit dry and dusty which is not i guess a problem in the Hut

koba

11th January 2012, 06:07

Me harping about the filter is about the fact that Canterbury in the summer is a bit dry and dusty which is not i guess a problem in the Hut

Not so much!

datfreak

1st October 2013, 14:41

Hi,
I'm new -sorry for the thread revive, there is some very good info here!
If I should start a fresh thread, please let me know.

I've got a 1980 h100a - is this the same engine as the mb100?

I want a fun street bike, probably not to full bucket racer tune.

The bike is STD at the moment, and I was hoping to use a cr85 reed , carby - and a expansion chamber off something that would match (or get one made up)

Is the cr85 reed correct to bolt up? I know it will probably need a spacer and a bit of a die grind , but should be ok as long as the bolts fit.

Any ideas for the expansion pipe? Or porting pics or measurements?

And is there a front disc upgrade, or is it easier to use another front end off another bike?

Thanks guys for joining and asking all these questions.

koba

1st October 2013, 15:19

Hi,
I'm new -sorry for the thread revive, there is some very good info here!
If I should start a fresh thread, please let me know.

Probably a good idea, then you can track it more and share some pics etc.

I've got a 1980 h100a - is this the same engine as the mb100?

No, but not far off.
The porting is different in the transfers and the exhaust.
I'm pretty sure the exhaust comes off at a different angle too.
That's the main difference, also some have points and others not.

I want a fun street bike, probably not to full bucket racer tune.

The bike is STD at the moment, and I was hoping to use a cr85 reed , carby - and a expansion chamber off something that would match (or get one made up)

Cool, you could race it anyway.
Not 100% sure about CR85, prob at least close.
Yamahay RD250/350 is a good easy to find starting point for a reed block.

You will alsowant to modify the inlet port to make this worthwhile, carving a port either side is the go.

Is the cr85 reed correct to bolt up? I know it will probably need a spacer and a bit of a die grind , but should be ok as long as the bolts fit.

Will likely need a spacer plate mede up, it can be bolted and devconned but a few welds and filling the rest with devcon is the best (Google Devcon)

Any ideas for the expansion pipe? Or porting pics or measurements?

It really depends on the result you are after, for a roadbike that still has a 4 speed you need to be conservative.
More later.

And is there a front disc upgrade, or is it easier to use another front end off another bike?

Some had front discs, I have an MB100 rolling frame if you are interested...
Front ned off something else is best if getting serious.

Thanks guys for joining and asking all these questions.

husaberg

1st October 2013, 15:46

The Air cooled CR80 reed is the same bolt pattern as the MB/H100 and will fit with a bit of work on the inlet opening.

the MB100 is a better starting point for a bucket as it has better finning and more transfer duration (kobs may have mentioned this.)
the RD250 inlet will fit pretty good after redrilling 2 holes and a bit of work with a chainsaw file to the two others and offer a decent inlet with a TZR250 carb (Dave has one or 2 for sale i believe.)http://www.trademe.co.nz/motors/motorbikes/parts-for-sale/performance/auction-642773065.htm
The H100 choke will fit the TZR carb too if he only has the chokeless one left.....

IF you get an aircooled cr80 cylinder you can use this as a template for the inlet

OH he has an ignition as well.
http://www.trademe.co.nz/motors/motorbikes/parts-for-sale/electrics/auction-642773826.htm

Or ask Mike re the cylinder he might be able to hook you up with a Brand new ready to race set up.

Ex pipe dimensions here is a simple calculator.
http://www.underdogsracing.com/fospipe.html

or here is the Bell based one.
http://www.bucketracing.co.nz/pipe.php

But get the gearbox 6 speed MB5 and match the porting to suit your track and your ability and match the pipe to suit.

find a honda front end with a 2'5x17 say CRB250 NC19 rim and brake fork set up and ya half way there.
Long term it might be easier to start with a complete chassis.
http://img195.imageshack.us/img195/307/img4351pf.jpg

datfreak

1st October 2013, 23:52

thanks Koba and Husaberg for this info.

My bike is the 5 speed w cdi.(ignition opens a whole other line of questions - will Jaycars programmable ignition kit run off the cdi pulse signal - are there real gains to be had etc --these qs can wait i guess)

I was just about to order the cr85 parts from ebay then read these posts -- anyone know if the cr80 air cooled reed is the same boltup as the later water models? The later ones are very plentyful on ebay, including aftermarket performance upgrades.

Those pipe calc programs are brillant! I have a spare header pipe in gc, which will help in measurements before I start butchering.

Koba - waht do you mean by "carving a port either side" in regards to the inlet? Cutting ports at the same height to the original inlet but further around the bore ?

F5 Dave

2nd October 2013, 07:37

husaberg

2nd October 2013, 16:22

Much as I'd like to sell some bits (I gave some Nigerians my bank details last week but once they'd had a look they left me a deposit) anyhoo, first I'd check your states laws for noise and moded bikes.

Also do a budget of what this will cost, including a million welding jobs . .to end up with a pretty woeful flexi 100 as a road bike. Best add everything in that list and ask yourself if that wouldn't be better sunk into an RGV.

the inlet is one narrow port. A smaller one added either side is safer than a dirty big hole.

Shit Dave you actually read is post properly. i obviously didn't.:innocent:

there is a thread on a US site for MB5's that covers road mods.
Not sure re the later reed, but just ask for the measurement.from memory the later ones have no bridge in the reed

I was real interested when i seen Mikes triple window inlet, as when mine was done i just replicated the large single port of the air cooled CR80.
I never had an issue with the rings but i seriously doubt mine had 30 hp like mikes. Maybe i wasn't greedy enough.
I should get Hilley to post some pics of my old cylinder........
To fit the reed a fair bit of material is removed.Plus cut outs for the reed screws
probably would have a port map somewhere but it was done all to bell other than the carb size and was real flat torque and not very peaky at all.

datfreak

2nd October 2013, 18:21

---snip -- i just replicated the large single port of the air cooled CR80.
I never had an issue with the rings but i seriously doubt mine had 30 hp like mikes... I should get Hilley to post some pics of my old cylinder........
... probably would have a port map somewhere but it was done all to bell other than the carb size and was real flat torque and not very peaky at all.

that is a very good idea copying the cr80 port design - if you have any pics that would be very helpful. When you say flat curve, is that flat enough to use as a road bike? I expect it to be a little difficult to get off the line, but ok once rolling.

I dont want to have a 30hp 100cc road bike (i kinda do but being realistic here) - if I could get 18-20 without it being crazy peaky, i'd be happy. Noise wise, it should not be too bad if I can find a good muffler.

husaberg

2nd October 2013, 18:28

that is a very good idea copying the cr80 port design - if you have any pics that would be very helpful. When you say flat curve, is that flat enough to use as a road bike? I expect it to be a little difficult to get off the line, but ok once rolling.

I dont want to have a 30hp 100cc road bike (i kinda do but being realistic here) - if I could get 18-20 without it being crazy peaky, i'd be happy. Noise wise, it should not be too bad if I can find a good muffler.

Earlier in the thread i posted a link to the 125cc kit made for the MB8,
everything i have read leads me to believe it would fit the MB100. as it seems it is a debored MB100 rather than a big bore 50,
Personally I would start from there.http://www.50cc.eu/en/product.asp?P=1782_cylinder-kit-honda-honda-mb8/mt8-eurocilindro-57mm
http://www.50cc.eu/plaatjes-onderd/1656.jpg

I have a port map for the cr80 but no idea where?
The only thing was the CR80 had a bridged EX.

well try this for inspiration
http://www.thumpertalk.com/topic/771316-honda-mb5cr80-hybrid/page-2

speedpro

2nd October 2013, 18:42

Re-cut the combustion chamber, lots of compression, use the standard reed block but with a single CF petal and remove the centre bridge, use an adaptor plate and fit a RD350 carb mount to the reed, 28mm Keihin carb, add an extra piston port each side of the existing port, some sort of decent pipe, and you should be looking at close to 20rwhp without touching the ports. To help the powerband you will be better off with another ignition. The old H100 is a bit "less" than a MB100 but not much. My son has the loan of a H100 powered bucket at the moment and it is a honey. Probably a bit less than 20hp but would be sweet on the road.

koba

2nd October 2013, 21:05

Ditching the head gasket is a good start or no $, just use Master gasket in place.
Seriously.

Not as good as recuting as speedpro says.
Maybe pay to check the squish.
If that doesn't make sense read a good book or seven on 2 stroke tuning.
Start with A. Graham Bell's book, "Two-Stroke Performance Tuning".

SwePatrick

3rd October 2013, 07:50

Earlier in the thread i posted a link to the 125cc kit made for the MB8,
everything i have read leads me to believe it would fit the MB100. as it seems it is a debored MB100 rather than a big bore 50,
Personally I would start from there.http://www.50cc.eu/en/product.asp?P=1782_cylinder-kit-honda-honda-mb8/mt8-eurocilindro-57mm
http://www.50cc.eu/plaatjes-onderd/1656.jpg

I have a port map for the cr80 but no idea where?
The only thing was the CR80 had a bridged EX.

well try this for inspiration
http://www.thumpertalk.com/topic/771316-honda-mb5cr80-hybrid/page-2

Yes you are correct.
MB8 is 49,5mm stroke and 45bore.
The cylinder fits 100 engine,, actually it´s made for the 100cc engine.
And the mb8 guys are lucky as it is a direct bolt on.
Almost all things are interchangable with CR80 up til -82 also.
Put an CR80 crank in an MB5 engine, weld a bit on blockscaskets and mill out room for the ports and skirt on cylinder, race hard!!
Bore it to 52mm with polini piston and you might tune it real hard, a friend has around 25hp+ at the rear wheel in his 'dragbike'.(probably 27-28hp actually)
and, 5gear gearbox from MB5 is a nifty little piece, can take all the power from mine 132cc project with ease.
I´ve got in the ballpark of 35hp+ at the rear wheel as we speak, if one could guess.
The 6 speed gearbox went boom almost immidietly :(
You can also fit clutch from lifan and songshen engines, to get a cheap uprated clutch.
I got an 6disc from YX engine with uprated CR85 clutchsprings.

Nice little engines theese hondas ;)

F5 Dave

3rd October 2013, 10:20

MT50 trailbike version had a 5 speed. Our MB50 (or MB5) had the 6. People use them here with 30hp rear wheel.

datfreak

3rd October 2013, 20:24

....
The cylinder fits 100 engine,, actually it´s made for the 100cc engine.
And the mb8 guys are lucky as it is a direct bolt on.

So this kit will fit mb100 and h100 bottom end? Anything special need to be done - ie head work, compression ratios etc?
Are the ports nice or need reworking ? it is a very nice price - i sent athena a email asking for more details.

Any easy front end swaps for the h100? Id like a spoked , light (small tube) setup. Does a mid-late 80's cr85 (disc one)triple tree fit without too much drama?
I need a new f brake cable, hopefully ill find a a hyd front end, so i wont have too:yes:

thanks koba for mentioning the 2 stroke tuning book, I got a oopy and read for a few hours.
Interesting - some of the blackart isn't so black anymore. Max port widths, ref to other high power 2 stroke bike port timings, runner shapes compression ratios etc etc awesome stuff. I wish its ignition section had more ref to other bikes ignition timing curves but its a wealth of info.

husaberg

3rd October 2013, 20:40

So this kit will fit mb100 and h100 bottom end? Anything special need to be done - ie head work, compression ratios etc?
Are the ports nice or need reworking ? it is a very nice price - i sent athena a email asking for more details.

Any easy front end swaps for the h100? Id like a spoked , light (small tube) setup. Does a mid-late 80's cr85 (disc one)triple tree fit without too much drama?
I need a new f brake cable, hopefully ill find a a hyd front end, so i wont have too:yes:

thanks koba for mentioning the 2 stroke tuning book, I got a oopy and read for a few hours.
Interesting - some of the blackart isn't so black anymore. Max port widths, ref to other high power 2 stroke bike port timings, runner shapes compression ratios etc etc awesome stuff. I wish its ignition section had more ref to other bikes ignition timing curves but its a wealth of info.

Somewhere i have posted the Bearing sizes, honda only used a few. watch for stem length.
A Gl145 front end would look right.

this is the bearing size you will have.
Upper: 22.5 x 41 x 12.5
Lower: 24 x 41 x 12.5
Honda MB-5-50 (82)
Honda MR-50/K1 (74-75)
Honda MT50Z, MTX50
Honda NSF50F (90)
Honda Z50A/K3-K5/RH/RJ, Z50A (71-76)
Honda Z50R (79-87), Z50RD (86)
Honda CR60R (83)
Honda ATC70/K1 (73-74), ATC70 (78-85)
Honda CL70/K1-K3 (69-73)
Honda CT70/K1-K4 (69-76), CT70H/HK1 (70-73), CT70 (76-82)
Honda SL70/K1 (71-73)
Honda XL70 (74-76)
Honda XL75 (77-79)
Honda XR75 (73-7Cool
Honda MB80, MBX80RFD/RSD
Honda MTX80/C
Honda XL80S (80-85)
Honda XR80 (79-84), XR80RF-R (86-9Cool
Honda ATC90 (75-85)
Honda CS90
Honda CT90 (68-79)
Honda SL90 (69)
Honda ST90K1-K4
Honda CB/CL100/K1-K3 (76-7Cool
Honda SL100/K1-K3 (70-73)
Honda XL100/K1 (74-75), XL100/S (76-85)
Honda XR100RP-R (85-9Cool
Honda ATC110 (79-85)
Honda CT110 (80-86)
Honda XL110/S (76-85)
Honda ATC125M (84-87)
Honda CB125/S (76-85), CB125T/J (78-81), CB125TT (90)
Honda CG125
Honda CM125T/J (82-85)
Honda CR125M/M1 (74-7Cool
Honda CT125 (77), CT125H/J/K (87-89)
Honda MBX125
Honda MT125 (74-76), MT125R/RII (77-7Cool
Honda SL125/K1/K2
Honda TL125/K1/K2/S (73-76)
Honda XL125K-3 (78-79), XL125S (79-85)
Honda MR175K (75-77)
Honda ATC185/S (80-83)
Honda CM185C (7Cool, CM185T (78-79)
Honda XL185S (79-83), XL185SH/SJ/SK
Honda XR185 (79)
Honda ATC200 (79-83), ATC200E Big Red (82-84), ATC200S (84-85)
Honda CM200T (80-82)
Honda XR200 (80-83)
Honda CB250N (Late Models)
Honda CBX250F (85)
Honda CM250C (82-86), CM250T (80-82), CMX250C/CD (85-87)

datfreak

4th October 2013, 22:30

Thanks husaberg - ill look into that. Yes the bearing kit does fit a lot of hondas.

The www.50cc.eu people got back to me and thinks that the 57mm WILL fit.
He updated the website today with tune up bits for the H100 ! See HERE (http://www.50cc.eu/en/parts_3.asp?Hg=All&Km=&M=Honda&T=H100&TA=HonH100&I=1363&Ag=14).
Some of the exhausts look neat - would be nice to know full specs though.

They also comfirmed that they will send to Aust-- so should also send to kiwi land :)

richban

4th October 2013, 22:33

Husa.

You got a bike yet?

husaberg

4th October 2013, 22:37

Husa.

You got a bike yet?

Not so much........

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=284754&d=1373185233&thumb=1
A little boy waits...

Well still Got the berg, got the Supermoto......ain't got the F-ing Nsr125 motor yet..........
But i guess you are meaning "the world longest Bucket build"
Got the chassis got most of the other bits wheel brakes etc...
Got many 1000's of dollars invested in casting my own cylinders..
Can't do f-all without the motor can't even do the wheels properly.
Should have brought a bloody FXR. (can't believe i said that) Or not sold off all the H100 engine stuff.

On the plus side pretty soon i will be lighter than the bike.

But you are right Rich.... if i don't see and Engine soon. say end of the month i am going to build up another MB100 only 125 with an 24mm oko and sling it in the RS125 chassis.
It will be like Daves only a "Honda" i guess

Grumph

5th October 2013, 05:56

Husa - has Wob managed to get John H to bring the NSR motor south ? i know John slightly and could collect and bring over at labour weekend.

mr bucketracer

5th October 2013, 07:39

Not so much........

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=284754&d=1373185233&thumb=1
A little boy waits...

Well still Got the berg, got the Supermoto......ain't got the F-ing Nsr125 motor yet..........
But i guess you are meaning "the world longest Bucket build"
Got the chassis got most of the other bits wheel brakes etc...
Got many 1000's of dollars invested in casting my own cylinders..
Can't do f-all without the motor can't even do the wheels properly.
Should have brought a bloody FXR. (can't believe i said that) Or not sold off all the H100 engine stuff.

On the plus side pretty soon i will be lighter than the bike.

But you are right Rich.... if i don't see and Engine soon. say end of the month i am going to build up another MB100 only 125 with an 24mm oko and sling it in the RS125 chassis.
It will be like Daves only a "Honda" i guessyou should of done the work your self and get job satisfaction from it.

Bert

5th October 2013, 07:48

Not so much........

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=284754&d=1373185233&thumb=1
A little boy waits...

Well still Got the berg, got the Supermoto......ain't got the F-ing Nsr125 motor yet..........
But i guess you are meaning "the world longest Bucket build"
Got the chassis got most of the other bits wheel brakes etc...
Got many 1000's of dollars invested in casting my own cylinders..
Can't do f-all without the motor can't even do the wheels properly.
Should have brought a bloody FXR. (can't believe i said that) Or not sold off all the H100 engine stuff.

On the plus side pretty soon i will be lighter than the bike.

But you are right Rich.... if i don't see and Engine soon. say end of the month i am going to build up another MB100 only 125 with an 24mm oko and sling it in the RS125 chassis.
It will be like Daves only a "Honda" i guess

Well if Wob-John H can get it to Palmy.
Then we might be able to fit it in the truck coming south for the BOB. then you can drive over and help for the day and maybe consume a little!!!
This is the longest build; no wait, Ivan........:killingme

F5 Dave

5th October 2013, 07:56

Not so much........

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=284754&d=1373185233&thumb=1
A little boy waits...

Well still Got the berg, got the Supermoto......ain't got the F-ing Nsr125 motor yet..........
But i guess you are meaning "the world longest Bucket build"
Got the chassis got most of the other bits wheel brakes etc...
Got many 1000's of dollars invested in casting my own cylinders..
Can't do f-all without the motor can't even do the wheels properly.
Should have brought a bloody FXR. (can't believe i said that) Or not sold off all the H100 engine stuff.

On the plus side pretty soon i will be lighter than the bike.

But you are right Rich.... if i don't see and Engine soon. say end of the month i am going to build up another MB100 only 125 with an 24mm oko and sling it in the RS125 chassis.
It will be like Daves only a "Honda" i guessnah mine is an LC now. But I did see those 125 kits and think would be an easy start.