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Bike won't start - Cam timing question

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Back again with a non-running bike, this time I'm down to the camshaft trying to troubleshoot the cause.

Following the FAQ guide I opened the valve cover and when the crank is at TDC the cam #3 and #2 arrows don't point straight up like the pics in the guide.

The exhaust is off by 2 degrees which is not much but the intake is off by 10 degrees. Is this the way it's supposed to be? I didn't count the 15 chain pins like a thread on the subject indicates 'cause I just found it and I'm away from the bike till tomorrow so I don't know.

By the way, I've posted about the dirty carb throttle plate, the spark plug resistor cap and the intake catching fire, checked the petcock, checked the trigger coil (b/w vs 3-yellow), valve clearance is within spec, battery has full charge.

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I would not worry about counting pins. On some Suzukis that is the only way to set the cams but the DRZ has marks on both cams so forget the pin count. When looking at the cam marks keep in mind the cam timing marks can only be off by a full tooth (or teeth). Would the marks be closer if the cam was moved a full tooth?

It is possible for the cam sprockets to slip in the cam. (they are pressed on not keyed) What that means is the cams can be timed according to the marks but the lobe position is not correct. This condition is a bit hard to determine unless it is way off. "Degreeing in" the cams is the only way to really tell if the sprockets have slipped. This condition is unlikely but possible.

Post the pictures and we will see what we can see.

What are the valve clearances?

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As suggested post pics.. Suggest three shots at least.

SET UP

Cam chain tensioner in and adjusted.

Piston set at TDC compression stroke.

1: Straight down into the timing mark inspection hole, try and keep aligned with the center of the crank, and straight in.

2: Right side of engine, even with the cams.. as if looking straight through the cams to the other side..

3: Left side of engine, even with the cams.. as if looking straight through the cams to the other side..

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Here are some pics,

DSC03449.jpg

DSC03451.jpg

DSC03455.jpg

This last one shows the #3 arrow pointing at the 10deg mark you have to look really hard to find the arrow.

Camangle.jpg

I'm also fabricating a fitting to measure compression with a regular pressure gauge, this will take me about a day to have some free time to weld and tinker.

I left the valve clearance readings at home but they are close to the high range (.3oo and .2oo mm), the lowest was an intake at about 0.230mm

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Cam timing looks fine. Not to worry. Cam chain might be a bit stretched but that is not stopping the motor from running

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Eddie how do you know just from a quick glance the chain is stretched? I mean I know what happens as far as timing shifting with a stretched/worn chain, but how to I know what is "too far"? I ask because I recently cut off my decompression mechanism. My bike has 12K miles on it and when I put it back together I noticed that the timing was a little ambiguous, so to say. I put it back together wrong (exhaust 1 tooth advanced) because it was honestly hard to tell when the timing marks were aligned properly. I noticed because it exhibited some telltale signs of advanced exhaust timing...

Sorry to derail the thread, but if your answer is what I think it'll be this will be fairly educational, and is the last straw on the potential winter rebuild for me. 434/RHC valves/FCR39/e-cams/e-base-gasket time may be drawing nigh.

It would be super sweet if you had stretched/non-stretched timing pictures with stock cams to post... :smashpc:

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the cam chain is worn out.
Cam timing looks fine. Not to worry. Cam chain might be a bit stretched but that is not stopping the motor from running

Thanks for responding so fast!

I also have to figure out how to check compression with the tools I have.

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A new timing chain would have all the marks line up and the 15 pin count. The ACCT is bad news for the cam chain. My old 04S timing marks were way off by the time I put in a MCCT and replaced the chain but it still seemed to run fine.

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Thanks, I still haven't found time to setup a leakdown tester.

Turns out I can't check compression with the auto decomp exhaust cam which is good news for me since the only reason I wanted to check compression is that I didn't feel any pressure when cranking it by hand.

So cam chain is worn but not the reason why it's not starting, compression is probably not the cause either but I still want to check before I put it back together again. I've never done a leakdown test before so I'm just curious.

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Thanks, I still haven't found time to setup a leakdown tester.

Turns out I can't check compression with the auto decomp exhaust cam which is good news for me since the only reason I wanted to check compression is that I didn't feel any pressure when cranking it by hand.

So cam chain is worn but not the reason why it's not starting, compression is probably not the cause either but I still want to check before I put it back together again. I've never done a leakdown test before so I'm just curious.

You should have compression when turning the crank by hand, if not, you found your no start issue.

Pull the cam, cut the decomp off, and do a compression check :smashpc:

Buy or build a leak down tester, and do that (better anyways)

If you have no compression, double check your valve clearance.. NO clearance = valve being held open = no compression.

HUGE clearance = valve bent, not closing = no compression

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Bad news from the leakdown test - 👍 Small air leak from exhaust port :ride:( Bigger air leak from the intake =(( Huge leak from the crankcase.

I'll pull the head to inspect the damage, any advice before I start (Do's or Dont's)?

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Here's some pics of the teardown, I thought there would be evidence of the compression leak to the crankcase. Should I remove the cylinder next? If the cylinder walls aren't scored rings are probably just worn, nothing I can determine just by looking, right?

DSC03462.jpg

DSC03459.jpg

DSC03461.jpg

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The cylinder shows little wear, the crosshatch can be seen clearly on three sides and barely on the front (exhaust) of the cyl.

So ... I know it's hard to say w/o mikeing the bore but it's a simple question: Do you think putting new rings will bring compression back or will it be money down the drain?

DSC03469.jpg

DSC03471.jpg

DSC03472.jpg

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Does anybody have the spec diameter for the bore and the piston?

It’s a 90mm bore.. And it is nikasil lined. If you can see the cross hatch, it can be cleaned up and reused.

The cylinder is much tougher then the piston. Unless debris get in the cylinder, they last a long time.

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