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Discussion Starter · #1 ·
I just did the cam mod and put a 13/1 compression piston in at the same time. Man this thing is like a ROCKET but it is a beyatch to start. I knew before doing this that the cam mod caused it to have trouble starting but i have to crank mine forever with the choke on while its hot. Any suggestions on how to fix this problem would be greatly apprectiated.
 

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How is it jetted? And what other mods are done to it?
 

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I don't know what you need to do to fix it, but my bike has the cam mod done to it and it doesn't have a hard time starting at all. Just thought you might want to know. I don't have the piston etc. done though. :|
 

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i really think you need to look at your jetting. I haven't installed my 13:1 yet, but soon and i have done the cam-mod. I can tap the starter and it literally starts in about half a second when cold and maybe turns over once or twice tops when warm.
 

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Originally posted by wildtxn@Dec 21 2003, 01:40 AM
i really think you need to look at your jetting. I haven't installed my 13:1 yet, but soon and i have done the cam-mod. I can tap the starter and it literally starts in about half a second when cold and maybe turns over once or twice tops when warm.
I wanted to try and help the fella out but he has not replied :wtf
 

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maybe he got wise and tried the rejetting deal. I'm interested to know as well. I've got the 13:1 GYT-R coming from bob but not looking forward to tearing everything apart for the install. I'm always afraid i'm going to mess it up. Not a bad mechanic, but no where near as good as I wish I was. Did the cam mod myself and rejetted and it runs absolutely great. Now if the mail would show up and I could get the rest of my stuff I would be golden :)
 

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I installed mine and it was not all that hard.
 

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How much stuff did you have to tear down to get to it? i'm assuming the valve covers have to come off along with the cams as well. I have to strip it down almost anyways to install the clutch basket, pressure plate, inner hub and the kickstart kit so may make it a one time deal.
 

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Originally posted by wildtxn@Dec 21 2003, 09:48 PM
How much stuff did you have to tear down to get to it? i'm assuming the valve covers have to come off along with the cams as well. I have to strip it down almost anyways to install the clutch basket, pressure plate, inner hub and the kickstart kit so may make it a one time deal.
I think I found this link somewhere..... :re



CAM MOD
 

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Originally posted by wildtxn@Dec 21 2003, 09:48 PM
How much stuff did you have to tear down to get to it? i'm assuming the valve covers have to come off along with the cams as well. I have to strip it down almost anyways to install the clutch basket, pressure plate, inner hub and the kickstart kit so may make it a one time deal.
uhhh ... sounds like someone needs a service manual 8|

after you pull the cams, unbolt and remove the head and then the cylinder will come off. if your not familiar with an atv/dirt bike 4 stroke top end I would strongly advise some help from someone experienced
 

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I have a copy of the electronic service manual and have access to a paper copy one from the shop.

I did the cam mod myself and didn't have too much trouble with it other than the frustration of actually getting it to turn back one tooth. I have scanned through the manual but not enough i suppose. I was assuming i would have to pull the valve cover, remove the cams and then the cylinder would come off after that allowing access to the area needing attention. My only worries were anything that i should pay really close attention to. I will actually do all of the work myself inside of the yamaha shop here where i am located. problem is the level of experienced mechanics around here is almost nonexistant. not a huge task to tackle myself, but haven't talked to too many who have done it already and just looking for any pointers if available. did you need a piston pin puller or did yours come out ok? My only other worry was to get all of the timing adjusted properly once reinstalled and whether or not you touched the valves at all in the process. I know it isn't going to be my easiest engine work i've ever done, but i'm going to tackle it nonetheless. I will try and take photos of the process and see if i can't come up with some better details when i do it.

Offroad ace, i don't need the links to the cam-mod. that's done, were discussing swapping over to a high compression piston.
 

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For the piston swap you will need to remove the cam cover, remove both cams, tie the timing chain up so it does not fall.

Remove the head bolts in the sequence specified in the manual, remove the head, assuming you removed the carb and mount that goes to the frame already.

Now remove the cylinder, careful not to scratch it or break the rings on the piston.

Now remove one of the circlips using job specific pliers.

Pull the pin, if its stuck use a socket of the correct size to persuade it to come out.

Install the new piston then the cylinder, set it at TDC, then install the head.

Make sure its at TDC then install the cams with the marks lining up. Now move the ex cam one tooth to go back to Cam-Mod timing.
 

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any tips on setting top dead center? did you use a dial indicator or just do it from getting it as flush as possible and lining up the timing marks on the crankcase?
 

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Originally posted by wildtxn@Dec 22 2003, 08:25 AM
any tips on setting top dead center? did you use a dial indicator or just do it from getting it as flush as possible and lining up the timing marks on the crankcase?
Use the marks on the flywheel and the case. Like you did when you done the cam mod.
 

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Where would you be able to find a good torque wrench?? Sears?? You need one to install the cylinder and head right?? I know the Head bolts have to be tightened to 7.2 ft. lbs.... but what about the cylinder bolts?

Also..... what torque wrenches are you guys using?
 

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Discussion Starter · #16 ·
I have a GYTR 45 pilot jet and a 172 main. The main shouldn't have anything to do with the starting so any suggestions on what I need to do to make the cam mod work?
 

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A couple guys I ride with had a problem with starting so they went up to a 110 on the starting jet. Starts right up!!
 

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Is that the starting jet in the other (the one other than the pilot) recess by the main? Seems like I noticed a 90 as standard.
 

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Originally posted by SoonerYFZ@Jan 1 2004, 07:13 AM
Is that the starting jet in the other (the one other than the pilot) recess by the main? Seems like I noticed a 90 as standard.
Yes that is it.
 

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I have problems with cold starting myself. I have the yz cam in mine, and the thing will NOT start!! I tried going down on my starter jet, as I was flooding mine out trying to start it. But then I quickly realized that it was flooding cause I had turned the motor over, over 100 times. I never thought about going up on the starter jet size. That actually helped them out huh??
I have since removed the yz cam, put the original cam back in and the thing fires right up. I then retarded it a tooth, and it takes a few more turn overs but still fires up. I wonder if it was just that, it wasnt getting enough gas on start.
You know whats weird though, is the stock starter jet on a yz is a 72 and the stock starter jet on the wr is only a 65, and they start up just fine!
 
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