Cam timing FXR150

[hmurphy]

Hey I thought I might as well post here just in case I'm not happy with my current method for timing my new cams.

My question is does anybody (particularly in the Wellington area) have a proper degree wheel and a spark plug type piston stop?

Currently I am using a large 360 degree protractor that is blue tacked to the extension rod for the 17mm socket that turns the flywheel. Needless to say I don't like it much at all. I am trying to think of more reliable ways, but never done this sorta thing before (done lots of reading and watching videos so I know what is supposed to happen though).

I am fairly sure a 10mm bolt would go down the plug hole to stop the piston but haven't tried it yet. Any help appreciated.

[koba]

Hey I thought I might as well post here just in case I'm not happy with my current method for timing my new cams.

My question is does anybody (particularly in the Wellington area) have a proper degree wheel and a spark plug type piston stop?

Currently I am using a large 360 degree protractor that is blue tacked to the extension rod for the 17mm socket that turns the flywheel. Needless to say I don't like it much at all. I am trying to think of more reliable ways, but never done this sorta thing before (done lots of reading and watching videos so I know what is supposed to happen though).

I am fairly sure a 10mm bolt would go down the plug hole to stop the piston but haven't tried it yet. Any help appreciated.

A good protractor is all you need but a more reliable way of fixing it to the flywheel is a must. You have access to machine tools don't you?

Modifying an old spark plug would work for a stop.

[hmurphy]

Just needa sort out a dial gauge (push pin type) then I'm sorted. Thought I had one sorted but that didn't end up happening.

So yeah... anyone trust me with their dial gauge? You know how good I am with tools... :innocent:

[kel]

I've just done my cam timing, used a 100mm 360deg protractor taped to the flywheel (true bucket racer style) with a wire pointer. The flywheel has a TDC mark on it that lines a with a casing marker (see manual) so its pretty damn easy to sort. I modified an old spark plug by hammering a piece of wire for finding true TDC (more bucket racer cunning). You will need to make up an adapter for the DTI as its shaft wont be able to get around the cam to the valve bucket I used a piece of 2mm wire. Have attached a photo of what I used as the description isnt that clear, have also attached photo of an attempt to check timing while still in the frame so you can see the DTI wire adapter/extension, you need to take the motor out and set it up on a bench. Dont forget to bump the compression while you have it apart. My motor certainly feels stronger but really needs to go back on the dyno to see what effect the changes have had.
231068
231067

Edit - dont use a 10mm bolt unless you want to wreck the valves, they'll smack against it as they open. You need something nice and thin like the spark plug adapter picture, even then you need to turn the crank nice and slow to make sure there's no contact. Once you have set the cam timing double check the valve to piston clearance at around 5 to 10deg BTDC, this is the most important part as any contact will destroy the motor.

[hmurphy]

Sweet thanks, I will make the same adapter for the gauge. I will be doing all of this in the frame though because I physically cant take the motor out at the moment. I have found TDC no worries now but just waiting until later tonight or tomorrow night when my dial gauge gets here.

Cheers heaps for your input and advice!!

[F5 Dave]

. . .unless you want to wreck the valves, they'll smack against it as they open. You need something nice and thin like the spark plug adapter picture, even then you need to turn the crank nice and slow to make sure there's no contact. Once you have set the cam timing double check the valve to piston clearance at around 5 to 10deg BTDC, this is the most important part as any contact will destroy the motor.

Gee these 4 stroke things sound fragile:innocent: All these bits of metal flailing about inside the engine, seems to be a design flaw.

[Arronduke]

Great info Kel...

How much differance was there from standard setup as per the manual?

[kel]

How much differance was there from standard setup as per the manual?

Manual dosent give valve timing figures just gives the info to set the timing between inlet and exhaust based on TDC and cam sprocket markers. I measured the standard timing as a reference point for changing the timing using sloted cam sprockets.

[TZ350]

What people often don't realise is, that its pretty easy to set the cam timing from scratch without any timing marks as cam overlap is prety much symmetrical about TDC.

If you have a garden varity motor in a pile of bits, one cam or two and no other information or timing marks the motor can be assembled with the cam inlet/exhaust lobes opening/closing symetricaly about TDC and it will run, a tooth out either way will be too much and obvious. And you can do this by eye, no timing gauges needed.

231338

Its only when you have adjustable sprockets and special grinds that you need more info to get the best out of the engine. But assemble it symetrical and it will at least run.

From my experiance the difference required on an adjustable sprocket will be less than one tooth on the cam wheel.

[kel]

From my experiance the difference required on an adjustable sprocket will be less than one tooth on the cam wheel.

Correct, on the FXR 1 tooth on the cam sprocket is approximately 20 deg at the crank.

[hmurphy]

This is all useful stuff you guys are saying. I have set the cams up in the way the manual says to (however at true TDC) and this is where I will start from. I will continue from here tomorrow or Wednesday.

I was told one of the cam sprockets didn't need to be shifted from its original bolting points but the other cam will need the sprocket to be mounted in a different place (requiring drilling of new holes in it). From your experience, did you have to modify the cam sprockets much?

Cheers

[richban]

I was told one of the cam sprockets didn't need to be shifted from its original bolting points but the other cam will need the sprocket to be mounted in a different place (requiring drilling of new holes in it). From your experience, did you have to modify the cam sprockets much?

Cheers

You may still need to slot both cam wheels to get it perfect. It will depend on the cam and timing spec as to how much you will need to slot the holes but it should not be much. Take your time and get it perfect to your spec sheet. If its not bang on it won't perform as good as it could. Look forward to seeing how she goes after all the work.

[kel]

I was told one of the cam sprockets didn't need to be shifted from its original bolting points but the other cam will need the sprocket to be mounted in a different place (requiring drilling of new holes in it). From your experience, did you have to modify the cam sprockets much?

Cheers

Ah that would be the nonsense about not altering the standard exhaust timing.
Dont know what cams your using but Im assuming you're dialing in standard cams, you will need to slot both inlet and exhaust sprockets for about 5 deg movement. Wallace has an excellent system of modification that makes setup super simple, dont know how much he charges but could be worth asking. 'marshland@marshland.co.nz'
Make sure you lift the compression ratio or you'll never see the full benefit.

[koba]

What people often don't realise is, that its pretty easy to set the cam timing from scratch without any timing marks as cam overlap is prety much symmetrical about TDC.

If you have a garden varity motor in a pile of bits, one cam or two and no other information or timing marks the motor can be assembled with the cam inlet/exhaust lobes opening/closing symetricaly about TDC and it will run, a tooth out either way will be too much and obvious. And you can do this by eye, no timing gauges needed.

231338

Its only when you have adjustable sprockets and special grinds that you need more info to get the best out of the engine. But assemble it symetrical and it will at least run.

From my experiance the difference required on an adjustable sprocket will be less than one tooth on the cam wheel.

I didn't know about this before I had a go at it on my old GSXR250. It bloody well worked. It still took me ages to decipher the standard markings but I eventually worked it out to confirm it was correct.

[kel]

Posted this in the ESE thread but should have gone here, bit of a double up but never mind.
Ive been playing with engine performance and evaluation software called lesoft. With all my FXR data entered (64mm piston, 12:1 comp, etc) its suggesting the standard cam timing can be tweeked to give it a bit more go. Have attached the simulators output graph for standard timing, inlet change only and optimised inlet and exhaust timing (the -deg refers to inlet open BTDC and the +deg refers to exhaust closing ATDC, its my own convention designed to confuse everyone but me), Ill update with a dyno run vs the simulators prediction in the near future. In the mean time if anyone else wants to give this software a go its available free from
http://www.lotuscars.com/engineering/en/engineering-software-downloads

232243

[hmurphy]

Ok so I have done all the measuring and my Intake Valve Opening shows that I am 2.85 degrees out but my lift is sweet. I will find a way to drill holes at maybe 92.85 degrees from the current holes.

My Exhaust Valve Opening is showing 152.025 degrees on the degree wheel but I am unsure what I am supposed to do with this figure. It is supposed to be 41 degrees according to the cam card. Am I supposed to subtract 152.025 from 180 (27.975 degrees)? That's the only thing I can think of that brings it close to 41 degrees but it seems a long way out.

[saxet]

Posted this in the ESE thread but should have gone here, bit of a double up but never mind.
In the mean time if anyone else wants to give this software a go its available free from
http://www.lotuscars.com/engineering/en/engineering-software-downloads

232243

Thanks for the link. I hope to try it out, if I can figure it out.

[saxet]

Ok so I have done all the measuring and my Intake Valve Opening shows that I am 2.85 degrees out but my lift is sweet. I will find a way to drill holes at maybe 92.85 degrees from the current holes.

My Exhaust Valve Opening is showing 152.025 degrees on the degree wheel but I am unsure what I am supposed to do with this figure. It is supposed to be 41 degrees according to the cam card. Am I supposed to subtract 152.025 from 180 (27.975 degrees)? That's the only thing I can think of that brings it close to 41 degrees but it seems a long way out.

Usually the timing specs are Before or After Top Dead Centre or Bottom Dead Centre,
BTDC, ATDC ect, I'm confident you knew that but just to confirm.
Not sure why you want to redrill your intake sprocket so much, would'a thought slotting would do.

If you need holes put in your sprockets try Carl (Karl?) at Cemeck, Fitzherbert st. Petone

TZ's post last page about symmetrical valve timing during the exhaust/intake overlap seems right.

[hmurphy]

Slotting? Does that mean to elongate the existing holes by a small amount?

[Henk]

That would be right.
If you can mark the cam and sprocket at the standard positions before you take it all to bits so you have some sort of known point to revert to if it all gets too messy.

[Ray LeCheminant]

That would be right.
If you can mark the cam and sprocket at the standard positions before you take it all to bits so you have some sort of known point to revert to if it all gets too messy.

Tamiya enamel paint pen does the trick real good!!! :woohoo:

[k14]

Posted this in the ESE thread but should have gone here, bit of a double up but never mind.
Ive been playing with engine performance and evaluation software called lesoft. With all my FXR data entered (64mm piston, 12:1 comp, etc) its suggesting the standard cam timing can be tweeked to give it a bit more go. Have attached the simulators output graph for standard timing, inlet change only and optimised inlet and exhaust timing (the -deg refers to inlet open BTDC and the +deg refers to exhaust closing ATDC, its my own convention designed to confuse everyone but me), Ill update with a dyno run vs the simulators prediction in the near future. In the mean time if anyone else wants to give this software a go its available free from
http://www.lotuscars.com/engineering/en/engineering-software-downloads

232243
Do you know if I used it for my CB125T and just modeled one cylinder would it be effectively the same? Seeing as they are essentially two independent singles on the same crank it should be ok? Unless anyone knows of some simulation software for twins?

[kel]

Do you know if I used it for my CB125T and just modeled one cylinder would it be effectively the same?

If your running independent exhaust then yeah it would be ok for optimising your cam timing, inlet and exhaust lengths. There's good gains to be had in matching lengths correctly. You'll have to do a fair amount of reading and measuring but once you have your model sorted its good fun to watch it optimise. ps it helps to have a really fast computer with plenty of memory, like my work machine :shutup:

[richban]

Hey Hamish

Since you have Kelford cams and you will have the tech card try running through this if you haven't already. Should all correspond with the info you have on the card.

http://www.kelford.co.nz/sole-purpose-of-degreeing-your-cam

[hmurphy]

Yah I used that page a lot, along with other videos etc.

Also....


I is done!! :scooter:

[hmurphy]

Hey did you guys need to use a smaller main jet after timing in your new race cams? I had to put the smallest main jet I have in the bike to get it to run close to ok, if I go bigger it gets worse. I was expecting to have to use a bigger main jet. It starts and idles well and takes throttle ok but currently HATES trying to pull from low revs. It used to love pulling from low revs. Obviously tuning issues at the moment that I will get round to. I'm back studying now so don't have heaps of time.

[F5 Dave]

Having never had to fool around with damn silly cam thingys I can't give specifics from experience, but you have changed the timing of the opening & presumably introduced a whole heap more overlap so it makes sense that the jetting will alter.

Try measure the compression, that will have dropped so you have obviously gone backward & you should reinstall the std cams, along with carb & muffler.


(worth a try)

[kel]

you should reinstall the std cams, along with carb & muffler.
(worth a try)

Im with F5 Dave. The bike will be quiet, reliable and fuel efficient, just as Mr Suzuki intended.

[hmurphy]

Ok so I put the std cams back in and I found my stock exhaust and carb and put those on too. I can't believe it... it's sooooo fast now!!!

Ok so anyone remember if they went up or down in main jet sizes with the race cams??

[hmurphy]

I have done a number of changes to the bike that seem to be working ok but I need a smaller main jet. I am using a PKW carb from the Akunar website (http://www.akunar.com/CARBURETTORS.html - the one at the top, 30mm) and I was wondering if anyone has any jets that are smaller than a 118 for this? It is very, very close to being right at the moment, but definitely needs to be leaner. I have tried bigger main jets and full throttle gets worse (it can't clear out at high RPM with full throttle) so definitely need to go a bit leaner than 118.
The spark plug looked fine after doing a plug chop, and it feels close but it misses a little up top.

On the bright side, the power is far more aggressive and it pulls pretty hard from reasonably low but WOW it pulls much, much better from mid to top.

Cheers

[kel]

so definitely need to go a bit leaner than 118.
The spark plug looked fine after doing a plug chop, and it feels close but it misses a little up top.Cheers

NO no no, 118 is run in standard motors, you need to go richer. Your best bet is to put it on a dyno with a gas analyzer (best move you can make when it comes to jetting) before the motor blows. The jets are standard Keihin hex jets available from most any bike shop. Seriously you will need to go richer

[richban]

NO no no, 118 is run in standard motors, you need to go richer. Your best bet is to put it on a dyno with a gas analyzer (best move you can make when it comes to jetting) before the motor blows. The jets are standard Keihin hex jets available from most any bike shop. Seriously you will need to go richer

You might be wrong there. This is a power jet carb. On my engine that has more compression and more flow than Hamish has. I run a 118 main. On the 30mm the power jet comes in very early might be worth disconnecting it and having a play. Just remember to go up to a big jet and work you way down. 135 maybe.

[kel]

You might be wrong there. This is a power jet carb.

I hadn't considered he might be running a power jet.
Is four stroke fueling compatible with power jets? Four strokes often use pumpers which is more or less the opposite to power jetting

[Henk]

If the PWK knock offs are a power valve job I'd be interested to hear what people are using to activate them. I have one of those OKO jobbies and the only thing I can think of with my limited knowledge of carbs is that somehow the air bleed I have blocked off is involvled, as for control I guess the answer will be "Get an ignitech"

[kel]

If the PWK knock offs are a power valve job I'd be interested to hear what people are using to activate them. I have one of those OKO jobbies and the only thing I can think of with my limited knowledge of carbs is that somehow the air bleed I have blocked off is involvled, as for control I guess the answer will be "Get an ignitech"

The air bleed on the outlet side is for balancing, the power jet is mounted in the top of the inlet and is activated by air flow. The knock offs we have dont have the power jet. Im lost to how they would work on a four stroke as the pumper richens the mix when you crack open the throttle, the power jet allows for lean main richen up on high revs via the power jet (very basic theory disclaimer)

[hmurphy]

Ok I will go to some bike shops and try get some more then. Yeah the bike has a lot more grunt through mid range but it misses up top and when I start going richer it just pops and splutters even more. The standard motor I was running a 120 instead of 118 because I wanted to run it as rich as possible and it ran fine on the 120.

So it sounds like I will definitely need to run it just a little bit leaner. The power jet must be doing a lot though. Is it really beneficial to disconnect it? I might try that and go for a test ride with a few richer jets.

Cheers.

[RDjase]

If the PWK knock offs are a power valve job I'd be interested to hear what people are using to activate them. I have one of those OKO jobbies and the only thing I can think of with my limited knowledge of carbs is that somehow the air bleed I have blocked off is involvled, as for control I guess the answer will be "Get an ignitech"

The power jet VM Mikunis I have on the RZ are just off air flow, The late TZ carbs have electronic power jet and are controled by the CDI.

I tried some power jets VM's on my LC and found it went better with standard VM carbs. If I had a dyno and heaps of time maybe you could set them up.

Some of the RZ power jet carbs have fixed/pressed in power jets in the float bowl and you can't do much with them. Blanking the pipes off and going bigger main is the best way

This has bugger all to do with a 4T engine but may help

[RDjase]

Ok I will go to some bike shops and try get some more then. Yeah the bike has a lot more grunt through mid range but it misses up top and when I start going richer it just pops and splutters even more. The standard motor I was running a 120 instead of 118 because I wanted to run it as rich as possible and it ran fine on the 120.

So it sounds like I will definitely need to run it just a little bit leaner. The power jet must be doing a lot though. Is it really beneficial to disconnect it? I might try that and go for a test ride with a few richer jets.

Cheers.

I tried a RVG (?) carb on my Sons FXR, seemed OK (ish) down low but when you gave it a big rev you could see the extra fuel pour out the power jet and it would run crap. Didnt do and more with that carb, as I got a 4 Stroke carb that worked heaps better. I think if the RGV had the power jet blanked off it could have worked OK with some more time and jetting

[Shorty_925]

If anyone has used a DRZ250 carb on an FXR i'd be interested to know what jets your running. Ive had not but trouble trying to find the right jets to be using, got a 135 main and 42.5 pilot and has a horrible part in the middle of the rev range. Ive been larger with both main and pilot and mixed and matched and found nothing that works as yet.

Revs out fine on the stand, but on the track its rubbish, coughs and farts, stab the clutch and clears it out.

[kel]

If anyone has used a DRZ250 carb on an FXR i'd be interested to know what jets your running.

What carb does a DRZ run? Im running Mikuni VM32SS pumper and a Keihin PWK knock off. The Mikuni needed the pumper action backed way off as it would cough when hammering the throttle open, it gives a hell of squirt of fuel but now it surges hard when opened. Mikuni mains between 165 and 190 depending on your state of tune

[hmurphy]

I have a Mikuni carb lying around too that I had tried with my stock motor. It also had a pumper on it which I hadn't got round to setting up but it didn't seem to need it much. The carb was pretty awesome and I was running a 165 main jet but getting the jets to test was gonna prove expensive and it was heavy and slightly too large (32mm).
I also struggled to get it to drive out of corners nicely because it seemed to make the ride rough. I was sliding like mad with it. Don't know how this new carb will be but I have been recommended it and so far it is very easy to change jets and work with. The stock carb was so easy to ride with haha, I was lucky to ever get it sliding a little with it.

[Shorty_925]

The carb is a Mikuni TM28 flat slide. Off the very bottom(like riding slowly out onto the track) it is perfect and with a slow build up of speed its fine, give it a handleful and then its coughs. Up very top it runs fine, but kinda anything inbetween its pretty average. The largest main jet ive got at the moment its 145 i think, I know I have a 140 and tried these and the bike ran worse than what it was running the 135 main. The clip on the needle is two off the bottom, and have been suggested to drop it down another. The state of tune is more or less standard, just a little grind for the manifold to match up.

The clutching it was the only way to ride around it and have some speed in the weekend. Will have to go order some larger mains and try them out. And the pilot, leave that as it is?

[F5 Dave]

You can't just compare jet sizes, every bike will be different, but more carbs will have different air correction jets so a 32mikuni will flow gas differently depending how it is set up.

[hmurphy]

Read this and look at the problems and solutions at the bottom...

http://www.4strokes.com/tech/4sjetting.asp

Read this if you want to understand more about how your carb works...

http://www.iwt.com.au/mikunicarb.htm

[kel]

You can't just compare jet sizes, every bike will be different.

Thats your fidley 2 stroke talking.
There are at least four of us running the same jetting on our works FXR's. If they could be any more similar in performance it would be sickening.

[richban]

You can't just compare jet sizes, every bike will be different, but more carbs will have different air correction jets so a 32mikuni will flow gas differently depending how it is set up.

I am with Dave on this one. All engines are different. even the ones that are the same.

[richban]

running the same jetting on our works FXR's.

How do you get a works FXR?

What's the spec on these things?

[Henk]

How do you get a works FXR?

What's the spec on these things?

Buy an FXR, work on it.
As for the specs, spread lies and mis-information so nobody knows what you are up to.

[richban]

As for the specs, spread lies and mis-information so nobody knows what you are up to.

Worked for me for a while. Not any more.

[koba]

The carb is a Mikuni TM28 flat slide. Off the very bottom(like riding slowly out onto the track) it is perfect and with a slow build up of speed its fine, give it a handleful and then its coughs. Up very top it runs fine, but kinda anything inbetween its pretty average. The largest main jet ive got at the moment its 145 i think, I know I have a 140 and tried these and the bike ran worse than what it was running the 135 main. The clip on the needle is two off the bottom, and have been suggested to drop it down another. The state of tune is more or less standard, just a little grind for the manifold to match up.

The clutching it was the only way to ride around it and have some speed in the weekend. Will have to go order some larger mains and try them out. And the pilot, leave that as it is?

Sounds like its running shit on the bit mostly metered by the needle.

You may have to play with different needles but possibly also the needle jet which is the brass bit the needle runs up and down in. If it's a common setup you should be able to buy alot of different sizes.

[hmurphy]

Wahoo! Just tested with a 115 jet and wow I didn't know the bike had a rev limiter haha. It's still running sliiightly rich I think (it could probably clear out higher revs better) but I'm not too worried and will leave it for now. I do have 1 size smaller main jet too (112) that I bought with the 115.

I do have one question though. Why would my throttle be harder to pull when the motor is running compared to when the motor is off? It's quite noticeable and very, very frustrating. Anyone had this problem?
I am getting a new throttle cable tomorrow hopefully because the one that came with the new throttle is far too long (it's excessive haha).

Other than that, my bike is all good to race and I have tidied up many parts of it. Can't wait to put a few laps in with it on Sunday.

Cheers for all the help

[richban]

The carb is a Mikuni TM28 flat slide. Off the very bottom(like riding slowly out onto the track) it is perfect and with a slow build up of speed its fine, give it a handleful and then its coughs. Up very top it runs fine, but kinda anything inbetween its pretty average. The largest main jet ive got at the moment its 145 i think, I know I have a 140 and tried these and the bike ran worse than what it was running the 135 main. The clip on the needle is two off the bottom, and have been suggested to drop it down another. The state of tune is more or less standard, just a little grind for the manifold to match up.

The clutching it was the only way to ride around it and have some speed in the weekend. Will have to go order some larger mains and try them out. And the pilot, leave that as it is?

I ran with one of these for ages then chucked it. Have lots of jets. It did work great with the standard engine. It should not be the needle Jet unless it has been fecked with. Might want to check if it is a bleed type or primary. Primary would explain the small main jet sizes also meant for a 2 stroke. Are you running a pod or any other filter?. If you have a pod ditch it and see what happens. I hate them. Those jets sizes sound rather small for a Mikuni jet. The standard TM28 comes with a 185 or something. I think my standard FXR used a 270. If you need any bits let me know I need a clean out. I have 3 TM 28s and shit loads of needles etc.

[Shorty_925]

I ran with one of these for ages then chucked it. Have lots of jets. It did work great with the standard engine. It should not be the needle Jet unless it has been fecked with. Might want to check if it is a bleed type or primary. Primary would explain the small main jet sizes also meant for a 2 stroke. Are you running a pod or any other filter?. If you have a pod ditch it and see what happens. I hate them. Those jets sizes sound rather small for a Mikuni jet. The standard TM28 comes with a 185 or something. I think my standard FXR used a 270. If you need any bits let me know I need a clean out. I have 3 TM 28s and shit loads of needles etc.

Yes running a steal pod as a just incase to stop a stone or something else going through. Had a look at it and had a look at the old boys carb which is meant to be the same and his runs perfectly smooth, noticed they were slightly different(both DR250 carbs), so measured it up and mine is actually a 32mm, and his a 28mm. Gone down to a 125 main and going to test and see what that does.

[F5 Dave]

those cheapo pod filters are worse than bad. Better to enclose the carb area with plastic real estate sign or whatever & have a entry out out the way of crud.

[richban]

those cheapo pod filters are worse than bad. Better to enclose the carb area with plastic real estate sign or whatever & have a entry out out the way of crud.

Again I agree with the Dave.

I have made all sorts of air box's most from a cheap $3 plastic containers. If you have the air draw from the top then it should keep out all the dirt and shit. If you can shield it completely from the engine even better. Nice cool air is good.

[timg]

It was suggested to me that I should use an airbox so I'm using the standard FXR airbox on mine. Seems to work well with my cheap chinese flatslide. I enlarged the airbox to carb rubber boot hole to accept a short bell-mouth. Cheers.

[Shorty_925]

Thought id give a quick update. The jet in there at the moment is working a whole lot better, not mint/perfect, but its ALOT better than it was and has been, so progress has been made and got a base to work from.