1986 Yamaha Moto 4 driveshaft ? rear issue- need HELP!!

**gd2227** · 02-02-2006, 05:40 PM

I believe either my drivshaft let go or my rear end went. While riding, I felt the driveline 'buck'. Next thing I know is the bike is in gear and you can hear the grind of ? the driveshaft. In neutral, it makes no sound. As soon as I put it in gear, it sounds like it wants to grab abd it moves the tire SLIGHTLY but then just grinds. The grinding does increase with RPM. I have talked to a few people with shaft driven bikes and they have never heard of a driveshaft letting go. I believe the issue is where the driveshaft connects to the rear axle.
With all that said, I need guidance on which way to go with this. Remove the whole rear swing arm and take apart the rear? Or should I just find another (rear axle assembly) and swap it in? If so, what years and bikes (sizes/ ATC's) interchange with my 1986 Moto 4 200?
Any advice would be GREATLY appreciated

.
Thanks

George D

**Howdy** · 02-02-2006, 06:05 PM

I just replaced a rear axle in a 86 Moto 4 200 10 days ago. lol

I have seen drive shafts break ( 3-4 of them ). They normally break at the universal joint. I have also seen the rear differentials break teeth as well. I just sold my last differential to another forum member that had one go bad.

Now, lets locate your problem and come up with a solution. Put the machine up on blocks. Make sure the tranny is in neutral and try to spin the tires by hand. Listen to see if any noises occure, if you hear noises find out where they are coming from. You might also want to check the oil in the differential for any pieces of metal / broken teeth. This can be done via a small stick magnet.
Report back to us what you find and we can go from there.
Howdy

**Yamahauler** · 02-02-2006, 07:50 PM

when my diff went out, there was just a big clunk coming from the rear end. It still drove, but what happened was 2 pinion teeth broke off.
Its fairly simple to take the rear end off, if you have a shop press, you'll whip right through it, the axles are hard to get out without a press.

**thefox** · 02-02-2006, 08:37 PM

Originally Posted by Yamahauler

when my diff went out, there was just a big clunk coming from the rear end. It still drove, but what happened was 2 pinion teeth broke off.Its fairly simple to take the rear end off, if you have a shop press, you'll whip right through it, the axles are hard to get out without a press.

I would check this out. I have heard of universal-joint going bad but I know the 85 YFM200 (the one with no suspension) is known for having the pinion go bad, just like Yamahauler’s did.

**gd2227** · 02-03-2006, 10:10 AM

Howdy,
I did place the machine on blocks and turned the rear wheels and the most amount of noise is coming from the drivers side rear wheel/ pumpkin. It is grinding- even out of gear.
Another thing I noticed is when the bike was off and in gear (to prevent it from rolling), it would roll like it was in neutral. It didn't matter WHAT gear it was in...
The bike runs great and i would hate to have to dump it...
Thanks for the input thus far. I am going to buy one of those service/repair manuals for the bike.

**Howdy** · 02-03-2006, 10:20 AM

I would be willing to bet your Differential gears are bad. I really wished I had a set to help you out here. Looking at the partsfiche for this machine, it appears the differential housing is the same as or simular to a 225DX. The bad part is my fiche don't give me the spex for this model so I can't tell if the actual differential gears are the same. If you pull it apart, count the teeth on the pinion and the ring gear and post them. We should be able to see what differentials would probably work.

Howdy

**gd2227** · 02-03-2006, 04:29 PM

Would the Moto 4 use the same rear as the Blaster? As other driveshaft-style yamaha's of 86-? Like the 220, etc? Just trying to plan a course of action if I have to replace the parts. The more I think about it, I believe what ever the driveshaft slips onto in the housing (guessing the axle), a few teeth are stripped off. If I have the rear of the bike suspended, running and in gear, both rear tires spin. As soon as any weight is placed on the rear, it just grinds...
I will remove the entire rear axle tomorrow. Howdy, if you have time, can you email me @ gd2227@cox.net and let me know if there are any 'tricks' on ripping apart the rear end?
Thanks again for your time and patience!

**Howdy** · 02-03-2006, 09:59 PM

The blasters are chain driven, so no it wouldn't work. I have another person that does the removal and installation of the differentials for me. This gives me time to keep searching for parts that have been requested. You can not imagine my work load right now. I'm on a 30+ Hour marathon and about to crash. And I am still at the shop doing ebay stuff and checking the forums. lol
Howdy

**smackkk** · 02-08-2006, 09:05 AM

Ijust found a moto-4 complete yesterday in a friends garage.....It is shaft driven.....I am awaiting word on a sell to me for parts.......If I get it I will hit ya back with pictures....I should know something by this weekend hopefully...?

**gd2227** · 02-09-2006, 04:37 PM

SMACKKK,

Please let me know when you find out.

gd2227@cox.net

**Yamahauler** · 02-12-2006, 03:39 PM

http://cgi.ebay.com/ebaymotors/Yamah...spagenameZWDVW
theres a 225 diff on ebay.
It should work.
Watch out for this guy's shipping price...$25 in the US

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1986 Yamaha Moto 4 driveshaft ? rear issue- need HELP!!