Starting after rebuilt/mods


30 replies to this topic
  • irok

Posted April 06, 2005 - 08:15 PM

#21

Frostbite: Wow...if you are getting that much icing...you must be freezin your butt off or just like to ride that much, or all the above!! lol :naughty: that is cool.

I think the dynamics of the bike totally change too in those kinds of temperatures. Are you using thin enough oil as recommended by the manual for those extreme temps? It could be that the different metals respond differently to temperture variations, and you might not be getting as good a seal as you should because of temp differences.

I would be interested to hear what you end up finding out...so keep us posted.

  • irok

Posted April 06, 2005 - 08:27 PM

#22

sk8rider: Thank you very much for your sympathy...I hope to get riding soon.

Mine also was done by Forward Motion. I haven't called him yet about this issue, I plan on doing that tomorrow...I am hoping he can help me out, as he has been so kind to do up to this point. I did a fair amount of research before I entrusted him to do my work, and have heard nothing but good things about Eric/FM there. I got everything as stated, the work was very clean and properly lubed per the manual etc, etc. Eric has been very supportive of my process and I DO NOT believe for a second that my result is that of his work. I firmly believe FM is very experienced and knowledgable about off-road motorcycles.

Everyone one I talked to up to this point believe my issue is a timing problem, and keep timing is extremely critical...with these motors in particular.

As soon as I hear any more from more research I will post.

Thx again.

  • Frostbite

Posted April 07, 2005 - 05:30 AM

#23

I think the dynamics of the bike totally change too in those kinds of temperatures. Are you using thin enough oil as recommended by the manual for those extreme temps? It could be that the different metals respond differently to temperture variations, and you might not be getting as good a seal as you should because of temp differences.

I would be interested to hear what you end up finding out...so keep us posted.


I run -52 Polaris antifreeze and 0W synthetic oil, which is the only one I've found that is still a liquid at -40.
I've been riding the same bike up here for 5 years years, and 75% of the time is below freezing and 25% is -30 or colder. I've never had this problem before. It just started after the engine rebuild. :naughty:

  • SXP

Posted April 07, 2005 - 05:42 AM

#24

Frost - Just put the original cams back in and see if the problem persists. The decomp mechanism on the Hotcam exhaust cam could be flaky and sticking open (when really hot) thereby keeping the exhaust valve open. That would definitely explain the loss of power AND the ability to cycle the the engine by hand with the kick starter. Give it a shot.

  • Frostbite

Posted April 07, 2005 - 07:39 AM

#25

Frost - Just put the original cams back in and see if the problem persists. The decomp mechanism on the Hotcam exhaust cam could be flaky and sticking open (when really hot) thereby keeping the exhaust valve open. That would definitely explain the loss of power AND the ability to cycle the the engine by hand with the kick starter. Give it a shot.


I like the manual decomp so I didn't order the Hotcams auto, but putting the stockers back in might be a good idea. It would eliminate one of the variables since I bored and cammed at the same time, and my jetting is still not dialed in.

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  • yz426em

Posted April 07, 2005 - 08:04 AM

#26

After readin threw this thread i must say anybody that has been in the process of rebuilding their motors will be nervous on the outcome. i just installed a new piston, hot cams intake and exhaust, fully rebuilt the entire bike and have yet to start it. This weekend will tell me if i have it right or not. To say the least it sucks to put a boat load of money into something and it brakes right away, i hope u guys get everything straight and have better luck, i also hope mine runs!!

  • irok

Posted April 07, 2005 - 09:07 PM

#27

yz426em: Good luck and best wishes. Hope all goes well with yours. I definitely would make sure you have done everything just so.

  • Math

Posted April 08, 2005 - 05:30 AM

#28

After readin threw this thread i must say anybody that has been in the process of rebuilding their motors will be nervous on the outcome. i just installed a new piston, hot cams intake and exhaust, fully rebuilt the entire bike and have yet to start it. This weekend will tell me if i have it right or not. To say the least it sucks to put a boat load of money into something and it brakes right away, i hope u guys get everything straight and have better luck, i also hope mine runs!!


Thanks! My turn to wish you good luck. I'll probably be done by Sunday so I'll let you know the outcome.

Later,

  • thumper_dad

Posted April 08, 2005 - 06:00 AM

#29

Hey irok, I'm VERY sorry to hear your experience. I don't have any tips aside from taking it back to the person who assembled the valve train for you. Maybe they can shed some light on how to move forward. I'm waiting for my head/cylinder to come back from Forward Motion. KPMI valve train and Wiseco piston. You've done a very good job at scaring the crap out of me! I hate other people working on my stuff too but you've got me thinking...

Anyway, I know you want to ride the thing but you might as well take the time to get things checked out before reassembling it. GOOD LUCK and keep us posted if you don't mind.

Take care.


This man almost took the words out of my mouth but I am sure who ever set up your valve train did it improperly, I use only Eric Gorr's Forward motion for my valve train work, I hate to see you pay twice for the same tyhing but you might want to atleast give Eric or Rich rohrich a call since Eric was the man who helped design the weisco piston and kibble white valve train for most dirtbikes applications., here is a link to there website HERE, the phone number is 1-630-289-5645


Good Luck

Rich

  • sk8rider

Posted April 08, 2005 - 07:31 AM

#30

Yep, just to make sure we're all on the same page, I wasn't saying that Forward Motion is necessarily at fault. I was just saying that as professionals, they should be able to diagnose the issue much better than, say, a guy like me! :naughty:

irok, you may already know this but if you can't get them on the horn, check out the dirtrider.net forum. They have a section specifically for Forward Motion questions. Just post your scenario and Rich Rohrich should respond back within a day. He's pretty responsive. :naughty:

Good luck

  • irok

Posted April 08, 2005 - 10:00 PM

#31

Hey guys...

I got a hold of Eric at FM today, and as usual was extremely helpful and nice. My head will be shipped to him this weekend to see if he can fix my f^ck up. Hopefully I will be able to get away with new valves/maybe seats. If not then I am screwed!

I can't stress enough to anyone reading this how critical the cam/crank timing is to this. This was my first engine rebuild ever, and I got all the expereince I need...if the head is good and just need new valves....Eric will get me set up there (while it will cost me for my mistakes, Eric/FM are very resonable, and I stand by the quality of work they do), a professional (i.e. the Yamaha dealership) will be checking the timing before running the bike. (unfort, I can't ($$ wise) send the whole motor to FM or they would be doing it.)

Thanks to everyone for support and replies, I will keep you posted as I move forward.




 
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