BAD news for my baby 426! help?

[dubee]

ok so i went out for a ride over the weekend and my 02 426 was running like a champ (like always). my buddy has this jump we jump and i was riding for about an hour before it happend.

My problem is the as soon as i jumped this jump and landed i was in the corner and it stalled as if i didnt have enough throttle on, so it stalled on me and right then i stopped and took a break, well went to fire it back up and it just kicked over ROUGH its not locked up but its tight.

1. it was running perfect

2. had oil in it (not sayin its very good i just went and got oil& filter the day before but didnt change it before ride:bonk:)

3. coolint level was full

4. decomp. lever is workin properly

NOTE: I did try something new that day and that was not using the clutch lever cause mine is so hard and it goes and gear so smooth with out it, i just took it out of the truck and if i put it in gear and pull cluth lever in the tire stays locked up.

Now the week befor this i was comming home from some tight trail riding and by the time i got to the open runway it was cuttin out at high RMP in fifth, so i thought maybe it was just cause it was hot it did quit by the time i got home if this helps anything.... please help i love this thing:ride:

Im gonna tear her down today hopfully im thinkin maybe burnt a ring up is my thoughts.?

Thanks Dubee

Edited November 2, 2010 by dubee

[dubee]

NOTE: i did try somethign new that cause my hand had a blister on the cluth hand so i was shiftin with out pullin clutch lever in but it was going in gear soo smoothlly i dont see how it would mess up, but when i pull the lever in in gear tire stays locked up???

[BDubb106]

Most bikes it will be very hard to spin the back tire even with the clutch pulled in with the bike not running unless your clutch is completely out of spec or has significant grooving. At least all mine do, but when running its not an issue.

As far as the bike running rough, how many hours are on the piston, valves, crank, bearings, etc.? Im interested to know what you find. May sound crazy but evey bike that Ive pushed a little to far on wear parts have always locked up only after I stalled the bike.

[dubee]

I dont know the hours as i bought it used, but i got the spark plug out and the clutch basket out, Now when i put pressure on the kick start the inner pully(gear or w/e) get kinda tight is that normal??

ok and then when i kick it over it will kick smooth for a lil while like everything is normal and then at random it is tighten up??

[BDubb106]

Sorry to have to tell you this but from your description it sounds like its a bearing... which means its either time to rebuild/replace your crank and main bearings.

[dubee]

yea sad to say... thats the direction it seems to be leanin towards but im still gonna try to rule everything i can out like maybe (wishing) clutch issue...i know im dreamin lol

These things really just go that fast with no warning at all?

[BDubb106]

Ummm sometimes they do sometimes they dont... sometimes there are obvious signs such as an increase in vibration etc. but usually theres very subtle signs that the average rider wouldnt notice (including myself). But there are guys who can tell you what they are and how to pick them out. Your gonna find its likely not your clutch though, the symptoms you described are almost always bearing related in my experiences. Good thing is you have to take the clutch out of the bike to get to the crank bearings anyways so you might as well rule/check that out on your way in there. While your in there be sure to repack any other bearings with grease, and replace any questionable seals, and clean the cases out really well while you have it split. Its an easy job and its probably past due anyways:thumbsup:

[dubee]

Yea atleast its not the begining of ridin season.. but ill be tearin her down in the near future.. i bet ill know everything about my motor after this one lol

But thanks for the help!!

[BDubb106]

Thats the sad reality in the world of dirtbiking... parts break and things need replaced. But I always look at the brightside though, tearing into the motor is the ONLY way your going to really learn your bike. Plus it makes things so much easier in the future to rebuild the bike and maintain the bike.

[dubee]

Should i buy a whole new crank or just press the new bearing on?

I know for sure i got to replace the main and crank bearings but what about the clutch shaft bearing?

[cowboyona426]

Should i buy a whole new crank or just press the new bearing on?

I know for sure i got to replace the main and crank bearings but what about the clutch shaft bearing?

The bearings for the crank are held in the case, they aren't pressed on the crank. Unless your crank is fubared I wouldn't replace it... 426 cranks are SPENDY. If the lower rod bearings are shot you'll have to take the crank somewhere to have it pressed apart and back together with the new rod kit.

Once you get the cases split go over all the bearings really well. Most of the bearings in there can be cross referenced to common bearings and purchased very affordably. There are only 3 proprietary bearings in there (possibly 4 I guess... not sure on the roller bearing on the countershaft) which are: the crank bearings and one of the bearings on the main axle. Crank bearings are about $45 a pop, the one on the main axle is around $30. The others can all be bought for $5-6 bucks roughly. I have the cross reference numbers if you need them ?

[dubee]

Alright thanks alot cowboy!! Once i get the bearings out I will post up the numbers so I can get the cross reference.

Yea i was lookin at some new cranks thanks god i dont have to take that path!

Thanks agian and will update as i move foward!

[dubee]

Btw have you started to assemble yours yet?

[cowboyona426]

Btw have you started to assemble yours yet?

No I haven't had time. I can post the bearing cross references later tonight hopefully.

[dubee]

Ok that would be great!!

Thanks alot!

[dubee]

Hey cowboy if you find some time can you post the cross reference for the bearings sometime?

Thanks, Dubee

[cowboyona426]

Doh... sorry about that! Stand by I'll post them for you.

[dubee]

Alright cool thanks, no big hurry

[matt4x4]

When you pull your flywheel and timing chain, carefully expect the gears that run the timing chain (crank end) - if there is noticeable wear - REPLACE your crank before your timing chain skips or you'll be into a whole lot of dollars soon through buying a new head or rebuilding your head.

[cowboyona426]

Finally found my sheet of paper with the cross reference info!

Right case half

Countershaft- 6203

Crank - proprietary

Main shaft- 6205

Counter shaft- 6004

Shift drum- 6905

Left case half

Counter shaft- roller bearing, I didn't cross reference or replace

Crank- proprietary

Main shaft- 6004 sealed on the outside

Counter shaft- proprietary