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YZ426 clutch problem

12 posts in this topic

Ok mine is starting to lerch when you are letting it out on the start gate. I have run Hondaline GN4 oil in it since new, except I just switched to Mobil Delvac 1, could this be the cause? I am going to switch back to the GN4 and replace the oil filter. I didn't notice any debris in the oil after I drained it, it did not smell burnt and was not discolored. Some people say that the clutch on these bikes do not get enough oil and that the clutch plates are dry, is this true?

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The Hondaline oil is a prob for a start! :D:)

The clutchs aren't flash on the 426's.

Do a search of the posts here.. its been covered quite a few times in the past.

------------------

--

**Ride it like you Stole it!**

Matt Porritt

99 YZ400F

Vist the Rubber Chicken Racing Online Shop

Discounts for ThumperTalk members.

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Originally posted by Matt Porritt:

The clutchs aren't flash on the 426's.

What does "flash" mean?

[This message has been edited by Hick (edited 07-28-2000).]

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Spiff,

To maybe save you the trouble here's a quick synopsis of what people have been saying 'bout the 426 clutch:

Oil type. Someone did mention that clutch was less grabby w/ Yamalube vs. Mobil 1. Poster switched to Mobil and then immediately switched back to Yamalube. I don't know what Delvac is, though.

Oil type counterpoint. http://www.eric-gorr.com/mototech/mototech_june_1999.htm

Oil Delivery. One poster’s mechanic discovered that end of clutch push rod was overly restrictive of oil flow (oil must pass by rod to reach clutch) and machined it to improve oil flow. If clearance between two pushrod parts (end cap thing and rod) seems tight or between pusrod end and main shaft I.D. then you may also have this problem.

Yamaha “semi-recall.” Check your basket for reinforcing ridges running parallel along each inside edge of each tang. If you don’t have these ridges contact your dealer (like yesterday because “bad” basket WILL grenade); they should warrantee part. “Good” baskets supposedly work better in addition to being less grenade prone.

Hinson. Many, incl. me, have experienced good results w/ Hinson basket. My clutch was grabby from day one and Hinson basket did make noticeable improvement. Only install snafu is rivets holding gearset to stock basket must be ground off/drilled out. I used oversize drill bit on inside of old basket (since this is getting trashed anyway) and drilled until I felt bit contact harder alum. surface of basket (versus relatively soft rivet). Cake. My clutch boss did have noticeable ridges, perhaps I should have splurged for the Hinson boss as well? Basket is ‘bout $225 American, boss ‘bout $175 (??)

Clearance. Check clearance between rear of basket and case. Mine, and at least one other poster’s basket rubbed a groove in the case where the head bolt boss is. Other poster had to remove some material from case to clear allen bolts (that replace rivets) on Hinson. For whatever reason my Hinson did not have clearance problems of stocker.

Noise. I still need help here. One poster, might have been same guy with clearance prob., had main drive gear coming loose (retaining washer was unbent, nut was backing off). I thought maybe clearance prob. was source of noise on my 426 but noise persists. At first I mistook it for drive train noise but I definitely have a clatter/whine coming from clutch side of motor. Starter gears? Bearings? Any tips on diagnosing this irritating (not to mention potentially catastrophic) problem will be greatly appreciated.

I am not a very good moto-mechanic but I don't trust any mech. w/in 100 miles (which isn't saying much in NM). So don't suggest that I visit "good" mechanic because around here there aren't any. I'm stuck with fixing it myself or putting motor in box and mailing to White Bro.s. Those of you with access to dealers w/ knowledgeable parts people, decent inventory and good mech.s should count yourselves lucky. I have to mail order oil filters, oil, plugs, everything. Parts guy at local Yam dealer did not know what "NGK" was. I am not making this up.

So I need all the help I can get!

[This message has been edited by Hick (edited 07-28-2000).]

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Hick, for plugs try clubplug.net you'll have to buy in bulk but if you change plugs a lot it'll save you some $$

Originally posted by Hick:

Spiff,

To maybe save you the trouble here's a quick synopsis of what people have been saying 'bout the 426 clutch:

Oil type. Someone did mention that clutch was less grabby w/ Yamalube vs. Mobil 1. Poster switched to Mobil and then immediately switched back to Yamalube. I don't know what Delvac is, though.

Oil type counterpoint. http://www.eric-gorr.com/mototech/mototech_june_1999.htm

Oil Delivery. One poster’s mechanic discovered that end of clutch push rod was overly restrictive of oil flow (oil must pass by rod to reach clutch) and machined it to improve oil flow. If clearance between two pushrod parts (end cap thing and rod) seems tight or between pusrod end and main shaft I.D. then you may also have this problem.

Yamaha “semi-recall.” Check your basket for reinforcing ridges running parallel along each inside edge of each tang. If you don’t have these ridges contact your dealer (like yesterday because “bad” basket WILL grenade); they should warrantee part. “Good” baskets supposedly work better in addition to being less grenade prone.

Hinson. Many, incl. me, have experienced good results w/ Hinson basket. My clutch was grabby from day one and Hinson basket did make noticeable improvement. Only install snafu is rivets holding gearset to stock basket must be ground off/drilled out. I used oversize drill bit on inside of old basket (since this is getting trashed anyway) and drilled until I felt bit contact harder alum. surface of basket (versus relatively soft rivet). Cake. My clutch boss did have noticeable ridges, perhaps I should have splurged for the Hinson boss as well? Basket is ‘bout $225 American, boss ‘bout $175 (??)

Clearance. Check clearance between rear of basket and case. Mine, and at least one other poster’s basket rubbed a groove in the case where the head bolt boss is. Other poster had to remove some material from case to clear allen bolts (that replace rivets) on Hinson. For whatever reason my Hinson did not have clearance problems of stocker.

Noise. I still need help here. One poster, might have been same guy with clearance prob., had main drive gear coming loose (retaining washer was unbent, nut was backing off). I thought maybe clearance prob. was source of noise on my 426 but noise persists. At first I mistook it for drive train noise but I definitely have a clatter/whine coming from clutch side of motor. Starter gears? Bearings? Any tips on diagnosing this irritating (not to mention potentially catastrophic) problem will be greatly appreciated.

I am not a very good moto-mechanic but I don't trust any mech. w/in 100 miles (which isn't saying much in NM). So don't suggest that I visit "good" mechanic because around here there aren't any. I'm stuck with fixing it myself or putting motor in box and mailing to White Bro.s. Those of you with access to dealers w/ knowledgeable parts people, decent inventory and good mech.s should count yourselves lucky. I have to mail order oil filters, oil, plugs, everything. Parts guy at local Yam dealer did not know what "NGK" was. I am not making this up.

So I need all the help I can get!

[This message has been edited by Hick (edited 07-28-2000).]

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The reinforcing ridges mentioned in the magazine (MXA) article are on the flat part of the basket, so the center hub has to be removed to see them (as the article says). Why did they show a picture of someone's finger holding the tang when all the tangs are the same? Because it's a Red Herring thrown up to disguise the real problem, which is lack of oil to the plates.

[This message has been edited by holeshot (edited 07-28-2000).]

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Originally posted by holeshot :

...Because it's a Red Herring thrown up to disguise the real problem, which is lack of oil to the plates.

I don't necessarily agree. While lack of oil could certainly contribute to broken basket a poorly made basket will break regardless. The oil issue also fails to address the basket/case clearance problems people, me incl., have been having.

I think there are a host of problems w/ 426 clutch, maybe because Yam engineers didn't have enough time to R&D them before production.

In addition to oiling, unreinforced baskets and clearance problems I may be able to add to list once racket in left side of my motor reveals itself in form of broken parts.

Still hoping/waiting for advice as to how to diagnose this problem...

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I have to agree with holeshot on this one. I initially diagnosed my problem as a lack of oil by soaking my clutch plates in oil the night before a race. The clutch operated perfectly for that session only. Then as soon as the bike completely cooled off and the oil drained out of the clutch, the problem reoccurred.

My mechanic and I then resorted to making some changes to the spiral grooves in the pushrods and this helped dramatically, so the key is definitely oil related in my opinion.

Stace

------------------

Pretty fly for a fat guy!

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Hick, Regarding your noise problem, have you checked the gear that turns the counter balancer? The gear is located under the main drive gear that turns the clutch. I found that when the nut that holds these two gears comes loose it will wear away at the square key that locates the gear to the crank. You must replace the 90 cent key before it destroys the keyway on the crankshaft. It is fairly easy to replace, just remove the clutch assembly then remove the nut on the end of the crank with an air wrench(if it isn't already loose!). You may find that the gear that turns the counter balancer is able to turn back and forth with out turning the crankshaft. If so replace the key and reassemble taking care to line up the dots on the counter balancer gears. Also loctite the nut and bend over the tab. This cured the noise problem on a friend of mine's 426.

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Hey guys try Golden Spectro 20 W 50 synthetic oil. Insiders at Yamaha say this is the best. Maybe that will halp solve some of the problems. Also, the Hinson Billet Clutch is the best way to go

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Originally posted by WRGUY:

Hick, Regarding your noise problem, have you checked the gear that turns the counter balancer? This cured the noise problem on a friend of mine's 426.

Thanks a bunch for the tip. I did notice some free fore/aft play in this gear while checking the main drive gear and nut, which was still tight. I will check for damaged/missing key and keyway tonight and update this thread...

Thanks again WRGUY!

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WRGUY,

Thanks for the tip, what you described is exactly what had happened to my 426.

Key was rocking from side to side in key way, allowing slack in gear-to-shaft movement. This wore edges off key plus put a longitudinal groove in it. Key way is slightly buggered but damage doesn't look significant to new key remaining in place.

It does look like retaining nut being too loose allowed key to walk partially out of keyway which created a small amt. of play.

Then the oscillating force from counterbalancer (push/pull/push) began wearing on the key.

This was the source of play in gear but I CAN'T BELEIVE I didn't see this problem...

So THANKS A LOT WRGUY!! You saved my rear :D

And thanks to thumpertalk and its moderator(s) for the forum to help solve ALL my problems (at least those related to my bike :))

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