Will I get my 100 ready in time for Taupo?

[F5 Dave]

I'll slang one out when the bits are back in my hands.

[F5 Dave]

Well a while since the last update. Two reliable meets since rebuild, but loss of power from get go to the tune of 3 or so hp and reduction of spread. Ring to bore. Leakage is 22% so still miserable and I don't understand why it's so bad but it's probably less than it has been before since started to use torque plate. I took the engine out again as the engine mount bolt broke a 2nd time.

I was using a captive nut on a bolt on engine mount plate as access was bad on LH side. So it broke at the threads, which is understandable. Answer really is to not use threads as an engine mount. Bit more grinding and I put the bolt in from the other side and will use a nut now new bolt is resting on its shaft through a hole in frame mount (12mm aly) with only tension on here threads rather than shear. Made the bolt on plate thicker as well.

Decided to measure primary leakage. SSSSSssssss. Wouldn't hold a sausage. Leaking through the rear devconed inlet. There's a crack leading down to the base from the con rod damage ages back. I is just need to find some time to remake the barrel. Won't be soon so I plugged it all up and within 1/2 doz tests managed to get it to hold some charge for a little time as opposed to no time. Leaking hp from both ends. Fantastic.

tomorrow I'll throw it back together and then look to re-ring the 50 which is a little down on power.

still some testing to do on the 100. I'd like to get the solinoid carb working but we'll see.

so will it be ready for ? . Erm. Tauporoa?

[F5 Dave]

Well everything is drippy. But the hp came back, now I know why. It'll no doubt start leaking again as the barrel moves again, but good for now. Gearbox leak was duff side case gasket so I've just custom cut another for the custom case. Now pump interface drips.

didn't have any joy with pj carb so a later day. Few more things like stinger join retention to work on so can't slip out & it'll be park it up ready and start on the 50:banana:

[F5 Dave]

Golly it's been a few month and have parked it since the GP. Went like a rocket but was so peaky that it was a pig around the hairpin wheelie or bog. Then it got slower as time went on.

bore worn past next couple of oversizes. Turns out I shortened the piston too far and that's why it wouldn't get ring seal, as it would cock in the bore. . . Unlike a cock.


so new barrel time. This time a I won't shorten the back of the back of the barrel so much and not the piston. I'll also triple port the ex like I did all those years ago, but I'll keep the ex lower and try get some spread back so it is rideable on tight ccts.

Port ripped it, have to make an insert fit so enlisting help. Sadly time is marching on and the BoB is closing in.

[F5 Dave]

cor time is marching on. I've triple ported the barrel & left the ex at std height at this stage. it is destroked so that alters things, but still a weird state of affairs. Its getting bored now as its impossible to measure up until the bore is right as it alters the timing. Looking after the kids most of the weekend but hope to get the barrel close to sorted & have a short time to then get welded up for the cut off ex port and water jacket. Just been looking at my pipe dimensions again (I borrowed an old design to get me started & it is well wrong now I look at it applying some of Wob's general rule of thumb percentages, but no time to change it now.

Must get some mid range & get ring sealing properly which the longer skirt should do. 3 weeks till Kaitoke so I can get a shake down run before the BoB.

[Drew]

cor time is marching on. I've triple ported the barrel & left the ex at std height at this stage. it is destroked so that alters things, but still a weird state of affairs. Its getting bored now as its impossible to measure up until the bore is right as it alters the timing. Looking after the kids most of the weekend but hope to get the barrel close to sorted & have a short time to then get welded up for the cut off ex port and water jacket. Just been looking at my pipe dimensions again (I borrowed an old design to get me started & it is well wrong now I look at it applying some of Wob's general rule of thumb percentages, but no time to change it now.

Must get some mid range & get ring sealing properly which the longer skirt should do. 3 weeks till Kaitoke so I can get a shake down run before the BoB.
Your pipe can't be wrong, it's the sweetest sounding bucket ever!

[F5 Dave]

aww that's touching

[F5 Dave]

Starting to get there, just a roughed out pic of the port

I pushed the barrel in the cases to see how much the full case reed inlet was obstructed. Answer: a lot. The last iteration had too much sleeve skirt removed so I've compromised and take the sides off and the area the piston doesn't get to.

[F5 Dave]

Another sunny day spent in the garage. Made all the bits off ally for the water jacket and plugged the holes for the aux port access entry's. Just need to get the welding done carefully. If it leaks it's no good as it can't be fixed easily so bit scary. Got the pipe bits tacked on ready for someone to weld properly. Ex timing is super low at 192 degrees for now. As easy to try just to see if I can get some spread.

[F5 Dave]

Well we're looking beauty all welded up, just ready for a hone & bolt it back together. Pipe modded (thanks Koba for welding).

Went to test though and sadly it leaks from jacket to port. That was always going to be a crucial weld, and hard as is thin there; going from 6062 to Honda shity casing. Note the porosity holes near o-ring,.

So now what was going to be ok timewise is a real issue and concern for the whole project. Has to be cut open to try again.

[speedpro]

At least you didn't end up with tread plate welded on

[jasonu]

Well we're looking beauty all welded up, just ready for a hone & bolt it back together. Pipe modded (thanks Koba for welding).

Went to test though and sadly it leaks from jacket to port. That was always going to be a crucial weld, and hard as is thin there; going from 6062 to Honda shity casing. Note the porosity holes near o-ring,.

So now what was going to be ok timewise is a real issue and concern for the whole project. Has to be cut open to try again.

Dave there used to be a radiator stop leak powder or granule available. You would add it to your radiator fluid. I used it to bung up a pin hole in a similar area to what I think you are talking about. Well worth a try before you go cutting your shit open.

[F5 Dave]

Yeah I've used that stuff before but I think this is too much. If it fails if it did work I could lose the water and fry the engine. We're cutting the front of the jacket off and trying again. Also I know from experience with my porous CPI 496 barrel that water leaking that close will blow into the engine leading to running issues.

Will weld and try smear Devon (or rather JB weld) over the affected area as belt and braces. That will mean the jacket going back on will need to only be tacked and glued so not to fry the epoxy. It should survive in use as covered by water not directly exposed to exhaust gases.

[koba]

Damn! this welding business seems fraught with danger.

[F5 Dave]

well its been a mission, but Karl had the idea of blocking up the port on the cylinder with some rubber and a tube & the other side with a pressure bung he had & presurising the heck out of it. fouund the leak and then another smaller one around a tricky corner. sorted & welded the jacket back on. back to kart guy to hone, but he was busy with enduro coming up, but he came through. back together tonight. I've done this enough times putting engines together that I didn't really need to start it, I'm not a kid. . . besides its almost 11 & I'd have to start it down the pavement by the neighbours (wouldn't want to wake my kids). But too late & don't really need to.[mixes gas] oh hears teh rain & its flogging it down (turns on gas).

BRWAAAHHH ring ring.

ok that's enough & didn't rev it at all, i'm not a total prick.

So SHWEETT! Bring on some fine weather on Sunday for the shakedown run.

Hmm, I guess I could slide off to the dyno now. . .


Nah. time for sleep.

[F5 Dave]

Should have gone to the dyno. Might have believed my det sensor and jetted up. Still it went strong until it nipped up. Can still turn it over but silly mistake. Over several piston types, destroke setup different piston I've always ended up with the magic 290 main so I guess I was suspecting that the sensor was loose again rather than it be that far out. And then it nipped. Did manage to fire myself up the road in the 2nd practise in the wet with a slick on the back it lit up.

seemed to not rev as high. Shift light wasn't coming on as regularly giving that impression too. Sounded good and seemed to have more engine braking.

[F5 Dave]

Oh and I checked the radiator. Bit sodding empty
Oh dear. Temp gauge was acting up. In the wet it was over cooling verified by touch after the practice.

[F5 Dave]

well classic 4 corner seize. that can mean too hot, too cold or small mainjet. all of these are possible.

I tested teh cylinder and it doesn't leak, but i remembered that the bike has an airlock due to the path of the water between the head & barrel. you have to raise the front wheel right up & run the electric water pump & i forgot this time. the water was still circulating but it was a bit feeble having to make it up the last bit of hose to the rad. the temp in the rain was waay too low so it could have picked up a bit then & just resulted in a seize later, or the low water could have caused localised over heating. the det sensor was picking up some det so main could have been too small even though no sign of det at all.

still i'm releived that it should be sortable and a trip to the dyno is in order.

[F5 Dave]

Well all back together and bled properly this time. Made a new bearing sprocket carrier out of ally and realised it was 1am on a school night. Dyno tomorrow.

[F5 Dave]

Well dyno day. But first issue was the sprocket bearing failed so had to buy a couple from Ripco before starting.

26.5hp on first run. Had to get more than Scott of course just to annoy him:innocent:.

clutch slips badly from 11000 thru to 13. Was running a 320 main from the 290 I ran with all other engines but clutch slip made it impossible to get consistent runs so we called it a day early.

still quite peaky it has to be said. With such a low ex I was expecting some low end jumbo. Pipe is totally mismatched so maybe that's it.

[mr bucketracer]

Well dyno day. But first issue was the sprocket bearing failed so had to buy a couple from Ripco before starting.

26.5hp on first run. Had to get more than Scott of course just to annoy him:innocent:.

clutch slips badly from 11000 thru to 13. Was running a 320 main from the 290 I ran with all other engines but clutch slip made it impossible to get consistent runs so we called it a day early.

still quite peaky it has to be said. With such a low ex I was expecting some low end jumbo. Pipe is totally mismatched so maybe that's it.bugger you lol , i would need just over 30 with my fat ass to stay up with it anyway

[F5 Dave]

well its still peaky. the pipe is now such a mismatch, but I don't have the time or funds to do anything about it for a while.

[F5 Dave]

Well I've ordered more genuine Honda plates, first time for the MB so maybe that will do the trick. Didn't have the spare money with BOB coming up. Malcom noticed the Fork seal leaking on the dyno, sheesh, bleeding money. The bearings I bought on sunday for the RS sprocket retainer were $50. I need a sponsor.

[F5 Dave]

Well the clutch only released a 1/2hp, was hoping for another 17. And a pony.

I'm away for over a week & then busy at work so not sure if will get to dyno again. Ordered some more jets as running larger than before, not likely to have time to try the other carb. Still have to do forks, maybe tonight. Tyre down to spots so arranged another 2nd hand one.

[F5 Dave]

Funny I thought I had done those forks but that's the thing about two similar bikes; these clearly hadn't been done this century. But now I remember swapping the later ones onto the 100 from the donor.

[Drew]

Funny I thought I had done those forks but that's the thing about two similar bikes; these clearly hadn't been done this century. But now I remember swapping the later ones onto the 100 from the donor.
Time for the shock to get a service too then maybe?

It works harder than forks, and gets less attention most of the time.

[F5 Dave]

Yeah and there's a funny thing. Robert has had my shock for both the 50 and 100 with slight revalve replicated between the two. But I can't remember if it was this one or the previous earlier shock that I sent up before I swapped from the donor.

Well over budget for this year. Still waiting to get my dirt bike ohlins back and wondering how much and how to pay for it.

[Drew]

Yeah and there's a funny thing. Robert has had my shock for both the 50 and 100 with slight revalve replicated between the two. But I can't remember if it was this one or the previous earlier shock that I sent up before I swapped from the donor.

Well over budget for this year. Still waiting to get my dirt bike ohlins back and wondering how much and how to pay for it.

He usually puts a sticker on shocks he works on. If it's been built for you, ya just need to match the fluid he used (centistoke rating is the only inportant number here) and any suspension tech can oil and gas that bad boy.

Which reminds me, I must fashion myself some tools to do my own shocks.

[F5 Dave]

He never or rather Denis never put any stickers on. I think it must have been the smaller body older shock. oh well, another bill. maybe after grafting on the SSS YZ forks for my GasGas as they may need a revalve and at least fork seals as a bit weepy. sigh

[F5 Dave]

Well I have some bigger jets and could try out the bigger carb but I'm too tired and lazy. Best work on being in good shape bike is going well enough.

[Yow Ling]

Best work on being in good shape bike is going well enough.

Might have left your run a bit late maybe, 3 days to get in shape including 1 day driving

[koba]

Might have left your run a bit late maybe, 3 days to get in shape including 1 day driving

Beer fixes that.

[F5 Dave]

Had a good nights sleep. That was worth it. I was a write off last year. This time of year for some reason

[F5 Dave]

We'll with the BOB been and gone there were mixed results. The bike was clearly the fastest thing out there although I never lined up against Scott. But it was still too peaky esp with the tall gearing. The temp stayed constant at 60* +\- 1* which was good considering the tiny pump. Cooler would be better but much better than air cooled.

the bike seized twice into the hairpin and was shite off closed throttle. Must check for air leaks. I put in a drilled pilot I found and had no more issues. There were two minor seizes on the rear skirt.

but the big issue is the destroke offset pin broke 2nd yr running. Fortunately the top end has survived. Hopefully the bottom will have too. The pin is broken on the flywheel side but a dinner party has stopped further autopsy.

So what to do? I need to run the 52mm piston but the pin either has to be remade better (expensive and still not certain) or the crank offset bored to fit the bigger pin. I avoided this in the first place as it will undercut into the shaft on the other side of the flywheel. Greg however says this is common practice on some old beaters so maybe it's worth a try.

the std pin was offset ground with generous radius. But clearly it's not good enough and peak power is a lowly 12,000 so further revving planed wil be more stress.

and I clearly need another pipe to get some midrange. So I'll modify the transfers as it's easier.

[TZ350]

but the big issue is the destroke offset pin broke 2nd yr running. Fortunately the top end has survived. Hopefully the bottom will have too. The pin is broken on the flywheel side.

The offset pins radius in the corner of the step maybe the issue with blending the radius at the transition of the offset. It may be possible to see where the origin of the crack is from the fracture lines.

304636 304638

Without a decent radius a crank will break sure as eggs.

304637

On this one it looks like the cracks origin is the top corner where the pin meets the crank web.

[Grumph]

Dave has previously said he's happy with the radius at the transition. What i'm not happy with is the amount of welding on the cases...I'd really like to see someone check just how accurately the mains are lined up...The MB cases don't have a lot of inherent strength/stiffness.

Any motor with a pressed up crank and mainshaft/crankpin overlap will have a reduction in mainshaft section area at the point where the pin shows past the web. If you're seriously concerned, chamfer the end of the pin - drive side only - and once assembled and aligned, weld the bastard...

As an aside, Dave, did the guy assembling the crank say anything about the pressure required to assemble it ? I assume it is a solid pin ?

[speedpro]

Pretty sure Dave's pin is dimensionally the same as mine though he got there by grinding the ends down to 20mm to fit the MB crank, starting with a 22mm pin. I had mine made from scratch by Heat Treatments. It had lots of "0"s in the cost. Possibly a need for heat or surface treatment after machining.

[F5 Dave]

If I understand heat treatment will affect the hardness of the surface but not the strength.

[Grumph]

If I understand heat treatment will affect the hardness of the surface but not the strength.

Depends on the material....If you're starting from a bought pin - bought as part of a rod kit - I wouldn't do any heat treatment post grinding the end down.
If you're grinding back from 22 to 20mm you're going through the case - or should be. If it's hardened deeper than that it's probably too brittle.
If you're making a pin from scratch - as i've done several times - the right material, EN36 is my preference, rough turn leaving a grinding allowance. Get it case hardened then finish grind. In the sizes we're talking about stress relieving shouldn't be necessary - and nor is hardening it right through...

Dave, when you press the broken pin out, have someone test the reduced portion for hardness. If it shows as being case hardened that deep, I'd say the pins have been too brittle - I'm assuming it's a bought pin ground down.

[F5 Dave]

Depends on the material....If you're starting from a bought pin - bought as part of a rod kit - I wouldn't do any heat treatment post grinding the end down.
If you're grinding back from 22 to 20mm you're going through the case - or should be. If it's hardened deeper than that it's probably too brittle.
If you're making a pin from scratch - as i've done several times - the right material, EN36 is my preference, rough turn leaving a grinding allowance. Get it case hardened then finish grind. In the sizes we're talking about stress relieving shouldn't be necessary - and nor is hardening it right through...

Dave, when you press the broken pin out, have someone test the reduced portion for hardness. If it shows as being case hardened that deep, I'd say the pins have been too brittle - I'm assuming it's a bought pin ground down.yeah bought pin.
Who would test that?

[speedpro]

At least one Griffith has a hardness tester, I think.

[Grumph]

[QUOTE=F5 Dave;yeah bought pin.
Who would test that?[/QUOTE]

In ChCh, Wallace has one so I'd ring small precision engineers who advertise they can do grinding...

(no reflection on Wallace's height intended....)

[F5 Dave]

Yeah actually Dave Griffiths was saying he had one at the BOB now I think about it. Thanks for the ideas.

[koba]

Pretty sure Dave's pin is dimensionally the same as mine though he got there by grinding the ends down to 20mm to fit the MB crank, starting with a 22mm pin. I had mine made from scratch by Heat Treatments. It had lots of "0"s in the cost. Possibly a need for heat or surface treatment after machining.

I remember you asking about interest to get a run of these done.
I'd be keen, depending on the final pricing, Dave, maybe Mike C?
would it make it that much cheaper do you think?
Or do we do go for a rule change lobby?

[F5 Dave]

Well here are some pics. Break between 1.1mm from radius and 4mm so not that near stress raiser. sort of torn.

Looking at it I'm keen to build a jig and offset bore to 22, there is actually a bit of meat in the webs. Just cant go 'through' as seal runs there, has to be done from inside the webs.

[speedpro]

Not running a counterbalance shaft Dave?

[Grumph]

i'd reckon that's been cracked for a while...And i reckon the crack's started from the pin bore..

i told you some time back that i've been known to hone and polish pin bores as some of the rod kits aren't very well finished.

Speedpro, is your pin solid or same/smaller bore ?

If the seal runs adjacent to the web, dave, it's possible to put a sleeve on the shaft at that point and run a seal with a bigger ID.

[speedpro]

Mine has a hole about 8-10mm, cannot remember exactly. I have not checked the finish inside. I had to have it hollow for balancing

[F5 Dave]

no balancer, reedblock goes right through it. It is smooth at idle, pretty vibey at 8,000 and smooth thereafter.

A sleeve huh? that could work.

Hmm, would have thought it tear from outside but interesting point.

[husaberg]

Worlds worst pic, but the cr80 from 81-81 has a 41.4mm stroke decent size mains so ends up with has overlapping shaft and pinboss
Can't find a decent pic though...... so this will have to do.
I was surprised when I seen it first time.

[F5 Dave]

Thanks. That looks like virtually same webs as MB

[husaberg]

Thanks. That looks like virtually same webs as MB

From memory the crankpin is 18mm the wristpin 13mm
The mains are mb100 size and the crankwheels are MB50 size. but that only from memory.
The pic is pretty shit but there is about 2mm overlap at least.........

[Grumph]

The biggest overlap on a pressed crank I've seen was a Benelli 650 twin. They must have invested most of the company's capital in forging dies cos all the early 4 strokes used the same crankweb forging. The 250 single was 57mm stroke and a smallish pin. The 650 twin was 58 stroke and as big a pin as they could squeeze in. At least 4mm overlap as i recall...
The cranks don't seem to give problems on those either - nearly everything else does....

[F5 Dave]

Think I will go ahead with the offset 22mm pin & undercut be dammed. it isn't actually as scary as I thought & means once modified no machining required.

[F5 Dave]

Won't be ready this weekend but I took the day off and all afternoon with dentist drill in the transfers. There's still a bunch more to do but dropped the floors to add about 20% area with stagger and new angles. Next stop Taumarunui.

[TALLIS]

Won't be ready this weekend but I took the day off and all afternoon with dentist drill in the transfers. There's still a bunch more to do but dropped the floors to add about 20% area with stagger and new angles. Next stop Taumarunui.

Maybe its time to rename the thread... will it be ready for taumarunui?:niceone:

[F5 Dave]

After a mornings racing I spent a couple of hours grinding ports. So much to do and no where near what an nsr barrel looks like. You can grind the bore ports bigger but you need to follow through with the feed area and in iron that takes forever.

So I'm up say 20-30℅ on transfer area,well see if that helps.

Crank almost finished.

[F5 Dave]

Trial bore, needs cleaning up and for size etc. Just encroaches almost to seal area but can run with std seal ok. Other side is brg so easy. I saw an RG150 crank & it is waaay into the brg area.

Offset inwards to destroke.

[Grumph]

What's it being done on Dave ? Mill, lathe, horizontal borer, black and decker workmate ?
I'd hope some way is sorted of matching the two webs...

With the Macchi cranks when we used big pins, the guy who bored them did it in a lathe in a jig he'd made up so as to do all crankwebs the same. Finish was internally ground...I think we've done six cranks now and never had one move or break.

[speedpro]

If the new holes don't line up EXACTLY the crank won't be able to be trued up. A precision jig would seem to be the go with possibly a near press fit pin to locate the original pin bore prior to oversizing in the new location. Be interesting to know how it's being done.

[Muciek]

What You think about this?



Here's link
https://www.youtube.com/watch?v=IWYQJ9Xfx1Y

[F5 Dave]

Mike has done it for me. He was DTIing it and boring then finishing it off in the lathe. Katie's crank came out spot on so I'm hoping this will be as good. No bush just bigger pin.

[F5 Dave]

Just got it back, apparently came in at .03 so that makes me happy considering the offset.

Now I just have to get my act together & sling it back into one piece.

Finishing the transfers is taking time.

[F5 Dave]

Well I should have done this days ago but with the will to live being drained out of me by work I've found it hard to get much done. So today with gusto I set in.
Start off by cutting a new centre gasket or rather 2 as I didn't like the first one. Then 2 base gaskets. Same reason. Pining for a std bike where you just order a stash of remade gaskets that fit straight up.


As I offer up the crank to the cleaned up cases I measure the divot cut into the Rhs seal run. Actually that will encroach one of the lip areas. Hmm, decide to fill the area with JB. When its dry I'll Polish it on the lathe. So another hold up.

I have left the barrel to get honed but there is more to do to try cup handle the transfers if only a little bit.


So will it be ready for Taumarunui?
I have a lap record to defend.

[Grumph]

Rather surprised you're using a center gasket Dave...My std practise for years has been to eliminate the gasket wherever possible.
Rub the cases on a flat abrasive board to true the surface and reshim the shafts accordingly. Three bond to taste...

Comes from doing too many Italian 4strokes which invariably develop a leak at the center case gasket.

[F5 Dave]

I actually run a super thick gasket for crank clearance.

[Drew]

I actually run a super thick gasket for crank clearance.

That seems like a very inaccurate practice, on a motor as highly strung as yours. Is there not a better way to do it?

Not giving you a hard time, it is structured as a sentence because I don't know the answer.

[F5 Dave]

They come std with a gasket & being a Honda it works well. I've just made
it twice as thick to give the relaxed clearance space on the rod (which widened the web slightly) to give more space to the mains. The case reed welded on means custom gasket.

[Drew]

On another subject, did you consider mounting the reed block at the front of your cases? Malcolm tells me that what looks like an engine mount on the front of an MB motor is in fact completely useless, could it be removed and have something similar to what you have as your inlet tract put there instead?

[speedpro]

I have a reasonable variety of alloy sheet from .2mm and on up thickness. I'm about to stack a pile together with thick bits each end, and cut MB100 base gasket shapes. I have been slowly going through the last stack I made.
You could easily cut an alloy sheet to the correct shape and assemble it all with Yamabond each side. I like the alloy base gaskets over the paper type as the thickness is stable.
It would work for the centre gasket as well. You could of course make it out of copper and leave it protruding on the outside like a cooling fin. It could also be left protruding on the inside in the gearbox to extract a bit of heat out of the oil which is bound to be getting a bit hotter than Mr Honda expected what with extra power and clutch abuse. A copper gasket along similar lines on the clutch cover could also be beneficial heat wise.

[F5 Dave]

Drew, I've seen that done on a sidecar, but it directs the flow through the crank which is no good. Plus my radiator, pipe & front wheel lives there.

[speedpro]

On another subject, did you consider mounting the reed block at the front of your cases? Malcolm tells me that what looks like an engine mount on the front of an MB motor is in fact completely useless, could it be removed and have something similar to what you have as your inlet tract put there instead?

The cylinder extends down from the gasket surface and effectively blocks any path to the area above the crankshaft but below the cylinder. There is also a bolt above and below that joins the crankcases that would inhibit placement. I've had a look at that and decided it wouldn't be worthwhile due to limitations.

[F5 Dave]

I use a .3 paper base gasket

[speedpro]

With this chatter about boring crank webs I've been thinking that instead of working to reduce the stroke why not increase the stroke, run 52+mm pistons and use a 24mm carb into a plenum.
With a stroke of 51mm(+1.5 over stock) and 52mm piston capacity is 108cc. If you have a rod with a 22mm pin and increase the stroke the full 2mm with an 1mm offset bored pin hole you get a stroke of 51.5mm and running the same 52mm piston end up with the engine at 109cc and 53mm piston makes 112cc and if you want to really push it go to 54mm piston for 117cc.
Rob has already proven that the 24mm carb is not actually a restriction.
You could have a velocity stack of the exact right length entering the reed block dead straight and the entry to the velocity stack would be the bottom of the plenum so anything that dropped out of suspension still went into the engine. Either that or have a small diameter hole in the base of the plenum that drained down into a similar hole in the cylinder or crankcases.
This would also have the benefit of not having to try and maintain some sort of acceptable mounting angle for the carb as it could be mounted at any angle feeding the plenum.
The plenum could also be an odd shape to fit around frame tubes without having too adverse an effect.

[F5 Dave]

The 'why not' might be the proximity of the rod to the cases. Already it almost rubs at BDC & needs a tickle. The metal isn't thick enough for a trench as we put on RZ cases. Some serious rework may resolve that.

[F5 Dave]

Barrel back from an extended stay getting honed, this time of year & all, but the good news was a light lick and its all straight, so the extra support is working well.

[Grumph]

With this chatter about boring crank webs I've been thinking that instead of working to reduce the stroke why not increase the stroke, run 52+mm pistons and use a 24mm carb into a plenum.
With a stroke of 51mm(+1.5 over stock) and 52mm piston capacity is 108cc. If you have a rod with a 22mm pin and increase the stroke the full 2mm with an 1mm offset bored pin hole you get a stroke of 51.5mm and running the same 52mm piston end up with the engine at 109cc and 53mm piston makes 112cc and if you want to really push it go to 54mm piston for 117cc.
Rob has already proven that the 24mm carb is not actually a restriction.
You could have a velocity stack of the exact right length entering the reed block dead straight and the entry to the velocity stack would be the bottom of the plenum so anything that dropped out of suspension still went into the engine. Either that or have a small diameter hole in the base of the plenum that drained down into a similar hole in the cylinder or crankcases.
This would also have the benefit of not having to try and maintain some sort of acceptable mounting angle for the carb as it could be mounted at any angle feeding the plenum.
The plenum could also be an odd shape to fit around frame tubes without having too adverse an effect.

The limiting factor on the big MB would appear to be the transfers...when you go as big as 54mm in the bore the top angles change - and not for the better. Passage volume is pretty much optimised for 100cc, not really enough room for the bigger ports needed for bigger displacement. that's why i was going to put a DT125 barrel on one...everything is optimised for 125 already.

just how far do you ride the scooter anyway ? looks like plenty of thinking time but a tad dodgy posting while riding...

[koba]

The limiting factor on the big MB would appear to be the transfers...when you go as big as 54mm in the bore the top angles change - and not for the better. Passage volume is pretty much optimised for 100cc, not really enough room for the bigger ports needed for bigger displacement. that's why i was going to put a DT125 barrel on one...everything is optimised for 125 already.

just how far do you ride the scooter anyway ? looks like plenty of thinking time but a tad dodgy posting while riding...

My 54.5mm barrel suffers from this badly, the transfers look horrid plus they are far too low with them being cutback with that roof angle.
I'm going to try it anyway.

[Grumph]

My 54.5mm barrel suffers from this badly, the transfers look horrid plus they are far too low with them being cutback with that roof angle.
I'm going to try it anyway.

Might well be Ok for kart tracks - more torque but less peak HP than a well developed 100 has been our result. Some sucesses but in hindsight we'd have been better to stay at 100.

[koba]

Kart tracks are different and most need spread of power over peak but I think on the balance of it the watercooled 100 is the way to go for an MB.

This 54.5mm barrel is watercooled so I won't compete with it but I think I will give it a try on my road MB100 sometime, just for giggles.

[F5 Dave]

Well here's my attempt at trying to get a reasonable curvature to the MB transfers. Clearly I've just stuck some inserts in & glued them in place. Next step is about 1/2 doz gluing iterations with grinding in between to get a finished job. I'll also have to look at the outside curve & match to the inner, but it was a bit naff before. Then there is the twist, but I'll try this first.

This should pull it kicking & screaming into the 80s. Wish there was a 100cc MC18 or newer to be starting with.

[Grumph]

Is this a fresh barrel without the water jacket ? if so at least you're free from the constraints of finning and can add material to the outside of the transfers to get a better curve...If not, it's been welded on once, pull it off again if you have to.

[FastFred]

I like your work, curving the transfer duct walls and eyebrow exhaust ports, very interesting.

[F5 Dave]

Its the same WC barrel I brought down to Chch Bob. I hate weld into Honda barrels, despite the LC jacket, but that caused enough issues.

[kel]

Hi Dave
I use an Pratley steel putty to fill and shape the transfer ducts. The putty allows the shape to be roughly formed by jamming into the duct with a small spatula then using a pre-formed tool to mash into final shape (as Mike also mentioned)

[F5 Dave]

Hmm that might be easier for the bottom bit, might try some. Repco it seems. The inserts gave me some consistent shape if I got them in the same place. Jolly hard this stuff in such small places.

[F5 Dave]

Well I've been tickling any tickling these transfers as
One, I didn't do a very good job initially. So hard to see up there
Two, the MB is a bit lop sided from std.

Anyway enough obsessing and just time to sew it all back together. I'd have liked to do a leakdown test but my new slip manifold means making an expanding mandril dodah.
Engine goes in frame tomorrow and dyno sometime after.

[mr bucketracer]

Well I've been tickling any tickling these transfers as
One, I didn't do a very good job initially. So hard to see up there
Two, the MB is a bit lop sided from std.

Anyway enough obsessing and just time to sew it all back together. I'd have liked to do a leakdown test but my new slip manifold means making an expanding mandril dodah.
Engine goes in frame tomorrow and dyno sometime after.post a picture of your dyno run , want to see how pecky it looks , the gt only seems to run of the main so hopfully time will fix that

[F5 Dave]

Really I was close to crying when I got home.

People seem to sling things together and get great results. But I have to find new problems. So I started with getting the woodruff key off but sorted that out.
First run full of hope and trepidation. I go to sleep every night thinking about my transfers or ex port. So I was hoping for some more spread. Heck even some more power.

What I got was 5hp less and 500 less rpm than the already peaky spread. Some jet changes reduced that to about 2.5 less but the spread is still gone.

Worse still is it jerks really violently on decell. Tried new plug and huge pilot. But I'm concerned to ride it like that.

[TZ350]

Worse still is it jerks really violently on decell. Tried new plug and huge pilot. But I'm concerned to ride it like that.

When mine does that, I often find that its over advanced.

[F5 Dave]

Hmmm intresting I was thinking of putting the timing light on it before pulling it down. Knock gauge wasn't going off particularly.

[TZ350]

Hmmm intresting I was thinking of putting the timing light on it before pulling it down. Knock gauge wasn't going off particularly.

I don't think the over advanced surging during over run on the dyno is a deto problem, more some sort of unstable resonant induced surging. I have seen it a lot and the cure for me was a bit of retard and maybe also richen it up a touch.

[F5 Dave]

Hmm ( more hmm) hold on I was running 15* flat for testing yet it was sometimes worse at 4-5 thou. One might have twice that advance in a normal curve. But was also at higher revs.

[husaberg]

Worlds worst pic, but the cr80 from 81-81 has a 41.4mm stroke decent size mains so ends up with has overlapping shaft and pinboss
Can't find a decent pic though...... so this will have to do.
I was surprised when I seen it first time.


Thanks. That looks like virtually same webs as MB


From memory the crankpin is 18mm the wristpin 13mm
The mains are mb100 size and the crankwheels are MB50 size. but that only from memory.
The pic is pretty shit but there is about 2mm overlap at least.........

I just measured up a CR80 aircooled crankshaft.
They are about a squidgy away from 3mm undercut on the drive side bearing only.
They have a 18mm pin and the flywheels are about 78mm diameter.
I guess this makes them pretty much the same as a MB50 but I think the mains are more MB100 size

[F5 Dave]

Well l fixed the quickshifter which was playing up. Still to put a timing light on it.

[F5 Dave]

Well the timing appears to be OK and at 15* is conservative. I cleaned out the carb internal passages, fixed the muffler bracket while avoiding the inevitable.
Took the head off and the bore is a bit polished maybe scratched, and there is a tiny chunk missing from the top of the B on one side where I'd lowered it for stagger. Pools. Barrel off, remove the JB weld from the face of the transfer roof. I'll need to skim the base and raise the A if I want to get there again.

In the meantime its ready to go back together. Which only leaves the question of the surging on decell. Will cleaning the carb fix it, or do I suspect some backlash issue perhaps with the clutch which on MBs can be wobbly as heck. Maybe its gone past a point.

[speedpro]

I've had an MB motor recently make some horrible gearbox area noise. The gears and shafts were all good when inspected. The problem was in 2 areas. 1st was the idler shaft between the clutch and the balancer shaft. The end of the shaft opposite the cogs runs in the plain aluminium of the crankcase. This hole it fits into in the crankcase was badly flogged out allowing the shaft to pivot about affecting how the cogs meshed. The other problem was the plain bearing the clutch spins on. It was badly worn allowing the clutch basket to wobble about which would have been pretty ugly for the primary gears. Ideally the bush needs to be removed and the basket machined for a needle roller, I think.

[F5 Dave]

I don't have the balancer but yes that was a reason my H100 was so cheap (free) as that was making a hell noise. But that plain bearing is worn on most of my baskets. I'll have another look at my stash. I ruined one basket at the GP year before trying to shim it.

[F5 Dave]

Well that's it, not taking the 100 to Taumarunui
Mild improvement but the stuttering is still there but perhaps only in 3rd. Might have to strip it all down and inspect.

But its power spread is still a bit crap. Bored of this.

[kel]

Well that's it, not taking the 100 to Taumarunui
But its power spread is still a bit crap. Bored of this.

That's no good at all. Its also one of the reasons I won't touch my porting, I know theres more power in there, but at what cost.
The KE has had the cob webs removed and is in the back of Rob's van, hopefully the fraying clutch cable will last the weekend. See you there.

[F5 Dave]

Yeah so I can strip it down again and fix the gearbox but I'm left with a bike that performed better before the mods despite having done `the right things` and it was too peaky for Tokaroa then. I struggle to see how I've lost like 2.5hp and 500rpm spread. It actually looks like decent workmanship.
I'm not convinced its the whole story.

[TZ350]

... I'm left with a bike that performed better before the mods despite having done `the right things` I struggle to see how I've lost like 2.5hp and 500rpm spread. It actually looks like decent workmanship.

Yep .... sorry to hear your having problems but it is a very familiar story, bikes are like children, they know when to play up.

[F5 Dave]

Well finally restarted work.

There is about 4mm float on the output shaft. I've put together MB cases many times, but I suspect a washer has jumped off so strip time.

Before I do I made a plug for the non std tube ex port manifold with an o-ring & wired it in with some goop. Will leak-down test tonight maybe.

I've bought some Vinamold to pour into the transfers to check them out for shape internally where I can't see them.

[F5 Dave]

Well its not leaking. Particularly.

[F5 Dave]

Couple of teeth broken off third gear set. Poos. I have a spare. Washer was there, but one was strangely the wrong type. Its of was a km too big and the thickness was 0.8 instead of 1.5. Wonder how that got there. Actually I'm thinking back to when I bought that box separate and who I bought it off. Oh well.

[F5 Dave]

Well the Trustrum Family barbeque finally gets used this summer. Good thing too as this stuff smokes somewhat.

Its also a bit like Napalm. Its hot and sticks to skin. You have to rub it to roll it off.

I sprayed a bit of silicon down the transfers and poured the Vinamold down, poked it & refilled the sink holes.

I've since pulled them out & its been illuminating. Pics later.

1kg Fibreglass shop $31 free shipping

Doesn't look pretty but works well.

[F5 Dave]

Ahh I never posted pics, or at least on this thread. I learnt a bit, like how I made a trumpet shape when I thought it was an even tunnel. Also inclusions where I couldn't see.

I've had another stab since these first moulds and gone further to rectify the issues, then moulded again with more work.

Ran out of patience to mould a 3rd time. Just want it back together for the weekend.

Pics, see how narrow the boost was? Next mould was much better but not far enough but no pics of those.

[F5 Dave]

Well its all back together, thanks Koba for the clutch basket I owe you something.

I think I'll just ride the next meet and see how it goes.

[TZ350]

I like the mold idea, it looks very useful, expect to see Team ESE trying it some time soon..... Thanks.

[F5 Dave]

Yeah melt it slowly, pour it slowly.

Well I'm ready for the next meeting. Hope I've got some power spread now.

[koba]

Yeah melt it slowly, pour it slowly.

Well I'm ready for the next meeting. Hope I've got some power spread now.

How'd it go?
I've had a quick skim of the results, I'm guessing you weren't on the 50.

[F5 Dave]

First couple running in/avoiding wet track/getting pilot near the right size.

It's fast, but its too hard to ride. You lose lot of time coming on power. 'nother pipe required. Also I'd like to make the back of the B's deeper with more angle to the centre. Very hard with dentist drill.

[F5 Dave]

Fuck I hate this thing. Dyno showed despite the careful transfer matching its barely struggled 21hp and compared to when first built 6hp down with 1500 thinner power band from an already peaky spread.

No wonder I was having trouble getting to the front.

So is it transfer mods or just some fundamental problem with an old highly unstd engine?

[Bert]

Fuck I hate this thing. Dyno showed despite the careful transfer matching its barely struggled 21hp and compared to when first built 6hp down with 1500 thinner power band from an already peaky spread.

No wonder I was having trouble getting to the front.

So is it transfer mods or just some fundamental problem with an old highly unstd engine?

That's a bit of a bummer Dave, I have been watch this exercise with interest.

What are your durations? Or maybe your pipe spec is now non matching compared to the early build. Or ... Maybe it's breathing better but your intake mods are restricting it (carb/reed stuffer)?

[F5 Dave]

The difference between October when I made the 3 port barrel and now is
1. crank rebuilt
2. transfers floor lowered to match piston BDC. Some filler on the inner wall to give them more curve and a slight tickle. All sorts of things that should improve things, not devastate power.

I'll leak test it again. It was pretty smokey on the dyno.

So the question is will the TZR engine fit an NF4? . . . .sigh.

[Bert]

?.......

So the question is will the TZR engine fit an NF4? . . . .sigh.

Bugger. Hate it when you put sooo much energy into something to have it turn to sh!t.

To answer the TZR question. I would have first though Not a rats chance in hell.. Wouldn't fit in a NX or TZ... Though the NF motor is a little more like a MX engine so it might get close I'll have a look see over the weekend.

[speedpro]

I hate it when that happens. Been there, and spent most of 2 years to get modest power out of an engine that was, I thought, gonna be super quick.

Just to cheer you up we've got 23.5hp out of Gary's motor and it's a sweety. The failure at Edgecumbe was the balance shaft ball bearing inside the gearbox disintegrating. How it never simply exploded I'll never know. It'll be all good for Tok'

[F5 Dave]

27.5 at 12,000 was likely to build to more at 13000 when I built a new pipe. But no point. Hopefully the world will stop and everyone will die.
Looking on the bright side.

[speedpro]

Have another snickers bro'

[F5 Dave]

See other thread, today is a bad day.

[speedpro]

Yeah I saw that. Can make life difficult for sure. I dread one of us losing a job.

[Drew]

I know nothing of 2 strokes, but I've followed this and the ESE thread as best I could with limited understanding.

Is there a basic fundamental being forgotten? TZ forgot that a 2 stroke wants not run as lean as possible when he went with injection, and was hampered further by an issue he knew existed, (piston meeting head), but discounted prematurely as merely an extreme circumstantial occurance.

This pipe that you know is lacking, could it be so far wrong as to fuck everything else before it starts?

I know I'm not being particularly helpful, but it bugs me that you do nothing but theoretically improve the bike and get fuck all for it.

[F5 Dave]

Ta yeah I'm going to go in looking for an issue first. Not sure what I'll do second. Hard to undo what I've changed

[Grumph]

Well if it's not a build issue, the only thing that strikes me is the lowering of the transfer port floors to match the piston height at BDC. I'm right in interpreting your post as this ? This is increasing the transfers time/area just as much as raising them the same amount would do.
The way the motor is running sounds very much like a transfer timing mismatch - and i've seen a few of them.....

Sorry i can't provide an answer. it could be as simple as the pipe but it could also be case volume related. Could also be the transfer stream shape and direction are now wrong for that cylinder.

As an aside i remember an aussie on another forum whose signature was "It's a poor husband who can't find his wife a second or third job"
Best of luck.

[F5 Dave]

Well if it's not a build issue, the only thing that strikes me is the lowering of the transfer port floors to match the piston height at BDC. I'm right in interpreting your post as this ? This is increasing the transfers time/area just as much as raising them the same amount would do.
The way the motor is running sounds very much like a transfer timing mismatch - and i've seen a few of them.....

Sorry i can't provide an answer. it could be as simple as the pipe but it could also be case volume related. Could also be the transfer stream shape and direction are now wrong for that cylinder.

As an aside i remember an aussie on another forum whose signature was "It's a poor husband who can't find his wife a second or third job"
Best of luck.
I'd lowered them the same amount on the last barrel which did similar good power but slightly higher revs

[F5 Dave]

Hmm, time seems to be disappearing & I haven't spent any more time on the 100.

So will it be ready for Tokaroa? (being that Taupo was last weekend).

[koba]

Hmmm, Mine is in a similar spot, might run, might not.

[speedpro]

I found out tonight that I won't be getting Gary's cylinder back until next Monday, and Sketchy still hasn't given me a delivery date for the billet water-cooled heads. Ah well, plenty of time to sort it all out, couple of workday evenings and chuck it in the van Friday night.

[F5 Dave]

Well the 100 is back together. I'd done a leakdown test & it failed spectacularly. I's found a piece of devcon stuck to the bottom ot the gasket surface that was holding it open and I could hardly pump it fast enough to find out where the leak was.

What I can't ignore is that the bore has a heap of ridges above the ex port. when I'd done a comp test (silly things on 2 strokes) but it dodn't push more than 150psi. not ideal by any stretch. It needed a rebore. I rang my local kart guy. and then again, and then on his mobile. He's in Melbourne. Ok that answers that question. sandpaper hone & back together.

But the good news is the leakdown test was rock steady. So I'm sure it will go better, much better than last test but maybe not optomim.


What I have decided that I can't be arsed going to the dyno before the GP. I could try the other carb or the reedblock, but I'd probably not learn anything & I'd be better off just getting some early nights tickling up catch bottles & packing.

As long as it can pass Kel in a straight line it'll be fine.

[koba]

Well the 100 is back together. I'd done a leakdown test & it failed spectacularly. I's found a piece of devcon stuck to the bottom ot the gasket surface that was holding it open and I could hardly pump it fast enough to find out where the leak was.

What I can't ignore is that the bore has a heap of ridges above the ex port. when I'd done a comp test (silly things on 2 strokes) but it dodn't push more than 150psi. not ideal by any stretch. It needed a rebore. I rang my local kart guy. and then again, and then on his mobile. He's in Melbourne. Ok that answers that question. sandpaper hone & back together.

But the good news is the leakdown test was rock steady. So I'm sure it will go better, much better than last test but maybe not optomim.


What I have decided that I can't be arsed going to the dyno before the GP. I could try the other carb or the reedblock, but I'd probably not learn anything & I'd be better off just getting some early nights tickling up catch bottles & packing.

As long as it can pass Kel in a straight line it'll be fine.

Let me get outta the way before the shooting starts! :2guns:

I'n NOT be doing the early night thing, as much as I want to.

[F5 Dave]

Well I've already done the catch bottles. We'll see if Kel reads this thread. Did I mention that I've been going to the gym for 2 and 1/2 months?:lol:

[kel]

Well I've already done the catch bottles. We'll see if Kel reads this thread. Did I mention that I've been going to the gym for 2 and 1/2 months?:lol:

No I have better things to do than read your silly thread.
I will bet you $50 and bragging rights (here for all to witness) that you will not pass me in a straight line in any race of the weekend
I'm serious about the gym, really enjoying it. Just wish I could wear dark glasses so I could get more perv time in

[F5 Dave]

hmm, nah don't think I'll take that bet. Last time I dyno'd it it was ~21hp with a far reduced spread. but at least I got a bite on my fishing trip, and inside a couple of hours. Not a bad day.

Are you that confident you won't take a lie down?

I was lying about the gym of course.

[chrisc]

Oh man, shit just got kicked up a notch! I hope reliability has been firmly built into that bike, it would suck to have a mechanical or a lie down and have to give blowies for life... or was that $50? We should do a GPR 4 stroke, Kel, Dave, Nathaniel, Ken drag race on the main straight after practice on Saturday. Winner gets a choc fish... or a blowy or some shit, Tim was offering something along those lines in my photo thread a while back? :Pokey:

[F5 Dave]

Well my bike finished last year, admittedly making a lot of smoke (think I traced that to a gearbox leak onto the pipe). I'd never cast a bet that it finished the race.

This year with rain forecast heck who knows if I'll even race, I might have to do my hair.

(maybe I should step up the trash talk but I'm not feeling the confidence atm).

[koba]

We should do a GPR 4 stroke, Kel, Dave, Nathaniel, Ken drag race on the main straight after practice on Saturday. Winner gets a choc fish... or a blowy or some shit, Tim was offering something along those lines in my photo thread a while back? :Pokey:

Great Idea!

[F5 Dave]

We used to run drag races for giggles at carpark events, but Tokoroa is hardly the place with that first corner.

Anyway mine needs a rebore at a min to get it back to full health.

[chrisc]

You wouldn't run the full length of it, half with the rest as braking area is enough. Google earth approximation is the straight being 115m long. Plenty!

[Pumba]

drag race on the main straight after practice on Saturday. Winner gets a choc fish... or a blowy or some shit


We used to run drag races for giggles at carpark events, but Tokoroa is hardly the place with that first corner

You boys are clearly forgetting that the air strip right next door to the track is the back is Tokoroa Drag strip :whistle:

[Henk]

You boys are clearly forgetting that the air strip right next door to the track is the back is Tokoroa Drag strip :whistle:

How many folk to lift a bucket over a fence?

[Pumba]

How many folk to lift a bucket over a fence?

Something like my fat arsed beast or one of these 50kg RS hybrid pieces of BS (and I include the GPR bikes in this mix)?

[Henk]

Something like my fat arsed beast or one of these 50kg RS hybrid pieces of BS (and I include the GPR bikes in this mix)?

Saturday night oi recon we can have a contest to see how long it takes any given team of two to throw you over the fence.

[Pumba]

Saturday night oi recon we can have a contest to see how long it takes any given team of two to throw you over the fence.

Where the hell is that dwarf when we need him

[Henk]

Where the hell is that dwarf when we need him

You're not that tall sunshine.

[Henk]

Pumba has just volunteered to be thrown over the fence as many times as required in a comment thing. BRing your throwing shoes.

[F5 Dave]

The drag strip idea is a good one if we could get permission to use it .

(que infantile jokes about stripping out of wimimns clothing)

[F5 Dave]

Well the bike started out promising but seemed to get slower. During the race, once I could almost convince myself to push on it became less sharp and couldn't gain on other bikes it could before.
I'm suspicious of the cooling and the gauge has decided to pack it in.

Then it went fut.

The clutch basket cush decided to unbutton itself and do bad things. Can someone import some legal 10yr old (2 stroke ones of course) bikes instead of these 30 yr old ones?

[koba]

I hear these Derbi things are quite the business!

[Sketchy_Racer]

. Can someone import some legal 10yr old (2 stroke ones of course) bikes instead of these 30 yr old ones?

RM85s are good Dave ;)

[Bert]

RM85s are good Dave ;)

Bingo...

:innocent:

[goose8]

RM85s are good Dave ;)

rm125s sound like more fun.

[kel]

Bingo...

:innocent:

Am I detecting a change in the air? Has anyone made a submission on this?

[F5 Dave]

Not sure I could stand another poxy Suzuki. I'm more a Yamaha man. But I have a GG & a Derbi + another Euro bike so maybe a KAYTOOM would be better for me. Its already orange.

[Drew]

Not sure I could stand another poxy Suzuki. I'm more a Yamaha man. But I have a GG & a Derbi + another Euro bike so maybe a KAYTOOM would be better for me. Its already orange.

Hang on, your Suzuki is always there to finish a meeting whenever you start the Honda.

[lodgernz]

Am I detecting a change in the air? Has anyone made a submission on this?

What? Allowing race bikes into a class that specifically bans race bikes? I hope not. That would be the end of bucket racing as we know and love it.
Yes we could create a new class that had separate races. We used to have one called F5 that had separate races. When the numbers went down it got tossed in with F4 everywhere except the GP.
Same could (probably would) happen with a MX class. No offence Sketchy, but if you want to race buckets you should have a bucket.

[Sketchy_Racer]

What? Allowing race bikes into a class that specifically bans race bikes? I hope not. That would be the end of bucket racing as we know and love it.
Yes we could create a new class that had separate races. We used to have one called F5 that had separate races. When the numbers went down it got tossed in with F4 everywhere except the GP.
Same could (probably would) happen with a MX class. No offence Sketchy, but if you want to race buckets you should have a bucket.

None taken, my rm85 bucket was a test to see how well they fit into buckets as a future potential. I have got my actual bucket running now which is what I was racing last round at kaitoke. However, I'm still firmly of the belief that 85cc competition two strokes should be made legal now.

[F5 Dave]

Anyhoo there is a thread about this debate. This is the thread to talk about me. . .


Nah, I got nothing.:yawn:

[husaberg]

Anyhoo there is a thread about this debate. This is the thread to talk about me. . .


Nah, I got nothing.:yawn:

What was the story with the clutch?
I think I have a basket here but some 18 year old has scalloped the fingers at bit.

[F5 Dave]

Too busy looking after the kids to get past whipping the cover off & witnessing the rear backing plate consentina itself, might be worth a pic when I get the time.

[Drew]

What? Allowing race bikes into a class that specifically bans race bikes? I hope not. That would be the end of bucket racing as we know and love it.
Yes we could create a new class that had separate races. We used to have one called F5 that had separate races. When the numbers went down it got tossed in with F4 everywhere except the GP.
Same could (probably would) happen with a MX class. No offence Sketchy, but if you want to race buckets you should have a bucket.

Oh yeah, didn't seem to end the class when race bike chassis were made eligible. Why should this be different?

Anyhoo, should there be a book running on how long it takes Dave to run out of patience with the MB lump?

[Bert]

Oh yeah, didn't seem to end the class when race bike chassis were made eligible. Why should this be different?

Anyhoo, should there be a book running on how long it takes Dave to run out of patience with the MB lump?

Actually Drew, never been a rule change around race chassis (not as far as I can recall >20years)

[jasonu]

[R RATED][/R RATED]
Oh yeah, didn't seem to end the class when race bike chassis were made eligible. Why should this be different?

Anyhoo, should there be a book running on how long it takes Dave to run out of patience with the MB lump?


Actually Drew, never been a rule change around race chassis (not as far as I can recall >20years)

Chassis have never been restricted in the Bucket class.

[speedpro]

That's because we never ever thought anyone would ever use a proper race chassis. Making a chassis was an option and there have been a few. Wheel's hub centre one and others, and lately the GPR ones of course

[F5 Dave]

I went the RS route as it was the cheapest way to upgrade (300 back then) but I'd swap a van load of them for a GPR.

[Drew]

Wonder why competition motors were excluded then. Has it always been 125 two strokes, or was it blanket 100cc whether air or water cooled?

[husaberg]

Wonder why competition motors were excluded then. Has it always been 125 two strokes, or was it blanket 100cc whether air or water cooled?

The original rules were no competition (I think they used the words factory hot up parts) they specified cams and pistons etc
103 or there about cc 2 stroke
130.5cc four strokes.
100cc four stroke forced induction
100cc four stroke open fuel. i think it was only avgas or methanol though.

[Drew]

The original rules were no competition (I think they used the words factory hot up parts) they specified cams and pistons etc
103 or there about cc 2 stroke
130.5cc four strokes.
100cc four stroke forced induction
100cc four stroke open fuel. i think it was only avgas or methanol though.

Cheers for that.

[husaberg]

Cheers for that.

I have been trying to find the original small coloured books I used to have a few.
They were ACU books .

[F5 Dave]

Air force boys bringing back Asian racekit parts for A100s and the like obsoleted std ones.
Don't remember open fuel. We were on pump gas in the late 80s when I started.

[bucketracer]

The original rules were no competition (I think they used the words factory hot up parts) they specified cams and pistons etc
103 or there about cc 2 stroke
130.5cc four strokes.
100cc four stroke forced induction
100cc four stroke open fuel. i think it was only avgas or methanol though.

100cc four stroke forced induction and methanol, now we could do something interesting with that.

[speedpro]

Air force boys bringing back Asian racekit parts for A100s and the like obsoleted std ones.
Don't remember open fuel. We were on pump gas in the late 80s when I started.

Brand new A100 race kit cylinders were available from Suzuki NZ in early '80s for $15ea. We bought all 5 that they had and it wasn't the Air Force guys. Yeah pump gas at the start though a few were scoring 100 octane as one of the large aviation companies used to leave it lying around and you could help yourself, evidently

[speedpro]

Me and an Army mate scored a fully race kitted A100 for $50. I got the 18" wheels and he grabbed the motor.

[husaberg]

100cc four stroke forced induction and methanol, now we could do something interesting with that.


Air force boys bringing back Asian racekit parts for A100s and the like obsoleted std ones.
Don't remember open fuel. We were on pump gas in the late 80s when I started.


I am not sure if it was. It was a long time ago now, probably 25 years ago. I think it might have been an either or situation,(only four 100cc 4t) but maybe Grumph or Mike G can remember.

[speedpro]

....or Mike G can remember.

Me remember? :blank: what were we talking about again?

[husaberg]

Me remember? :blank: what were we talking about again?

Whether the 4t 100cc were allowed methanol and other open fuels and supercharger/turbo or it was an open fuel or forced induction in the old original rules.

[Grumph]

This is the wrong thread for fuel discussion, it's all about dave and what he's done wrong....

However, as i remember it, everything was pump fuel - which was taken under the ACU regs of the time to include avgas...except supercharged fourstrokes which were limited to 100cc but could use open fuel. Pre '89 this would have included Nitro. The Methamol/Nitro option disappeared from buckets when it went from other classes too. I walked out of that years conference in protest....
Background - I'd been involved with the fastest F1 bike in NZ for 3 seasons using a meth/Toluene blend plus tony Mcmurdo's F3 and F2 bikes using the same blend plus big jolts of Nitro...I felt justifiably aggrieved that having out thought the opposition we were being banned.

[Kickaha]

it's all about dave and what he's done wrong....
Everything

[husaberg]

This is the wrong thread for fuel discussion, it's all about dave and what he's done wrong....

However, as i remember it, everything was pump fuel - which was taken under the ACU regs of the time to include avgas...except supercharged fourstrokes which were limited to 100cc but could use open fuel. Pre '89 this would have included Nitro. The Methamol/Nitro option disappeared from buckets when it went from other classes too. I walked out of that years conference in protest....
Background - I'd been involved with the fastest F1 bike in NZ for 3 seasons using a meth/Toluene blend plus tony Mcmurdo's F3 and F2 bikes using the same blend plus big jolts of Nitro...I felt justifiably aggrieved that having out thought the opposition we were being banned.

Yeah but was that at the same time as the Robert Taylor TZ250 yam and BMS f1 framed 750 Ducati protest counter protest F2 saga.
I never knew the f3 GPZ500 was on the juice too though. I have that KB article somewhere with the write up on the F3 bike.

[Bert]

Yeah but was that at the same time as the Robert Taylor TZ250 yam and BMS f1 framed 750 Ducati protest counter protest F2 saga.
I never knew the f3 GPZ500 was on the juice too though. I have that KB article somewhere with the write up on the F3 bike.

I'd be interest to learn a little more about the GPZ500... Have one in the shed and was thinking about what to do with it...

[husaberg]

I'd be interest to learn a little more about the GPZ500... Have one in the shed and was thinking about what to do with it...

Grumph did it...........I bet his memory would be more actuate than any reporters blub

[F5 Dave]

Paint it pink and green.

[Bert]

Grumph did it...........I bet his memory would be more actuate than any reporters blub


Paint it pink and green.

Boat anchor was my first thought... I was a little disappointed at the engine weight.

Sorry Dave. I'll transfer this conversation to the GPR tread...

[F5 Dave]

Well Mike came over and we got it ready for Kaitoki. Light 4 corner seize, but also noted the carb was loose. I'd just tried to get an RS shroud to fit and it was a squeeze against the carb but I think it ejected the carb back so it would have been leaking. Put a bigger pilot in to be sure.

Mustang turbo intercooler pump now fitted and waay more powerful. . no time to dyno it but hopefully it goes OK. I'll swing by at lunchtime and come have a look and wish I could ride it.

[F5 Dave]

Pump seems to work well.
Clutch didn't. Was slipping on track apparently and couldn't get a run on the dyno due to slip.

So what with extra plate genuine new plates and preloaded to the max, stiffer springs were the way forward. Ordered some last week but specified a modest 10% increase. Put one in the vice head to head with a std one. The std one compressed more.

Slapped them in. Lever pull seems OK. Hopefully enough to stop the slip.

So another thought is the lack of midrange and loss of power after the last round of transfer mods. The inside curve is much more pronounced. But I didn't open the outers as the didn't seem to need it. But I'm now thinking that I need more volume to be readily available.

[kel]

So another thought is the lack of midrange and loss of power after the last round of transfer mods. The inside curve is much more pronounced. But I didn't open the outers as the didn't seem to need it. But I'm now thinking that I need more volume to be readily available.

Volume of the transfers ducts was discussed in the ESE thread, but I don't remember what the general rules were :facepalm: I'd guess that the duct having less volume would effect the top end more than the mid. My transfer ducts after filling the inner and grinding the outer walls have pathetic volume compared to something like an RS125 yet it has a reasonably fat power spread. Did you change any of the port timings?

[F5 Dave]

No my mods were going from std transfers but non std timings (as a result of barrel positioning & the destroking process), in this case 128 & 126.

Mods: Opening the bottoms to TDC where they were proud before. Reshaping the inners for more curvature & matching to the lower floors. A's were brought forward at the bottom triangularly toward the ex, B's were moved back a tickle, a bit of fill to increase the A's angle approaching 25deg.

About 4 redo's where Vinamold showed up irregularities.

Result; 3-4hp gone & curve range squeezed 1000rpm less. Kinda the opposite of what I was expecting. They are pretty small ducts compared to say an NSR or RS barrel even accounting for 25% shrink.

[kel]

128 & 126.
It sure sounds like you have done everything right but that's really conservative timing for a triple exhaust port. Going from single to triple exhaust ports I widened and raised my transfers from 128 to 132deg to match required time area (and have since matched the inlet). With raising the A ports angles have you cut a hook into the B's to flush out under the A's?
Could you have too much blow down? I've seen it said that you can't have too much blow down but Rob certainly proved that to be false.

[TZ350]

Could you have too much blow down? I've seen it said that you can't have too much blow down but Rob certainly proved that to be false.

To much blowdown for the RPM was my problem. Pipe Tuned length - Blowdown STA miss match.

[F5 Dave]

OK well here's the googly thing on this barrel: -I started off low on the exh. Peak power is only at 12k, later I was going to crank everything up to 13k but I was trying to see the effect of a super low exh before I wound it up to my intended and fairly conservative 196. Currently it is 192. yeah. Still made 27.5hp when first run which is ok for 12k.

The power curve between the single port 199 deg barrel (before it goes oval) & the triple with std transfers & 192ex are identical but at lower (400) revs on the new one. You would have thunk 7deg lower ports might have had more of a pronounced effect for midrange power.

The pipe is wrong, too short header, too long diffuser, but it is better than the RS125 pipe I'd worked with.

[kel]

192ex ... You would have thunk 7deg lower ports might have had more of a pronounced effect for midrange power.

The pipe is wrong, too short header, too long diffuser, but it is better than the RS125 pipe I'd worked with.

I think it is having a more pronounced effect i.e. the problem in the exhaust design is even more apparent with the lower exhaust port timing and the effect of your latest transfer duct changes, I'd put money on (or maybe not :shutup:) the out of sync return exhaust pulse is messing up your transfer flow especially if you have a low primary compression with that case reed set up.
But then its probably just those silly flappy things you use to control inlet timing.

[F5 Dave]

Golly, well that hasn't happened for a while. A dyno session where everyone went away pretty happy. Several bikes and good results.


I got some clutch Springs made 10℅ stiffer. Result +4hp hp and 1000rpm spread so 26hp and same curve on the way up. Still a HP and 1/2 and say 700rpm down but its big progress. Just from springs.

[speedpro]

4hp worth of heat not going into the transmission as well. Surprised the clutch was slipping.

[F5 Dave]

New Honda plates too. Maybe it hits too hard but either way it was loosing it all the way up the curve. Pipe is still wrong but I bet it can kick some now. Pity I'm not up to riding it.