Thumper600

Oh yeah cheers mate, might just clean it out and see what happens. hopefully not more $$$.

Hey guys, I'm not all too sure how the Yamaha Dual Intake System works, when my bike is under heavy throttle it seems like it's being restricted in the top end of the revs, only a new problem was, going mint a couple of weeks back. Is it something a home mech can look at or do I need to take the carb set up into a shop. Cheers

Thanks guys, I'm pretty sure I've found the problem, when I was warming the bike up today I saw a bit of smoke blow from the joint where the pipes meet. I'm going to silicon it up and put a new clamp on, hopefully that sorts it out.

Alright cheers guys I'll test it out this weekend and get back to ya. Hopefully I can sort it out.

Hey, I've got an '81 XT550 and it's backfiring alot, mainly when I come off the gas. It also does it when I kick it over whilst holding the decompression lever, usually just after an unsucessful attempt to start - it always starts on the second or third kick both hot and cold. The bike has always backfired, I'm sure most of the older big singles always have but these far more aggressive sounding, super loud buggers! Any kind of help is appreciated, cheers.

Hey Jonesboy, Wouldn't this happen if the battery is disconnected? Have you checked the terminals?

Have you checked all the fuel lines/filters to make sure they're not blocked?

I just cleaned the carb out and made sure that nothing was blocked and it seems to still be doing it but not as bad.

I can't even see a breather! I think we have found the problem. Haha

Cheers for the reply. I've checked all the fuel lines and the filter, all sweet as. I don't think it's starving for gas. Gaskets look OK, but could do with a change, I got the bike off a guy who didn't know what maintenance was, the bike was caked in about half an inch of clay when I got it. I think I better just take the carb off and give it a good clean, but I don't think that's the problem.

Hey everyone. Recently I was riding my XT and I noticed that in 5th, and only 5th, it climbs through the revs nicely, but won't rev out like it does through all the other gears, if the back wheel is spinning in 5th, it revs out fine, but when it has any kind of load it refuses to go any faster. This happens at about 120-140KMPH. Could this have anything to do with the carb, or the second jet not starting like it should, or not getting enough air? or anything like that? Cheers, Thumper. EDIT: It is a single cylinder 4 stroke, single carb with the YDIS. EDIT2: I was taking a video on my phone to show you what I meant but I dropped it and it smashed(excellent)

1986 DT125 Side covers/radiator shrouds not on, this was just after me testing the top speed, about 135KMPH, quite impressive for such a small bike I thought. 1986 XT400 and 1982 XT550 - will post pics as soon as I get them

Have you ridden a bike before? Other than the scooter? You should be fine if you don't like ride like a maniac. Remember to keep it maintained. 24miles everyday, I hope you have some wet weather gear.

Just incase anyone ever has this problem and searches these forums. To get to the gear shifter shaft, you must remove head, barrel etc, split the crank case (on these bikes also removing the swing arm). What a mission to change such a small part! Oh well, might aswell give her a freshen up while it's apart!

What got me into bikes. I was fishing on a beach one fine day, about 5 years ago I would have been 13-14. I believe it was a TT600(80's model) thundering past me, he must have been doing atleast 120kmph. Just the sound of the motor made me love it. Since then I have loved the big displacment singles. Alot of my friends who are into bikes too tell me I should just be rid of my thumpers and get a smaller, newer bike, which will have more power! but it's just not the same. However I should probably get them registered soon, before I get some fines. Oh - and get my license.

Cheers guys

Cheers for the responce, however as the diagram on that link shows only one shaft the XT 400 (identical motor to the XT 550 but not XT 350) has two seperate shafts, (diagram; http://www.bikebandit.com/houseofmotorcycles/1982-yamaha-xt550j/o/m8363#sch224700) When it happened, I thought to my self "Great, no dramas, I'll just go home and swap them over" I removed the right side cover, but I then saw a shaft protruding from the motor, but it was parallel to the actual shifter shaft, and no way to remove the broken shaft itself. Surely there must be a way to change it without removing the motor. Most things on this bike are not a problem to fix, but this has me baffled. Cheers!

Hey there, I'm Ricky. Recently brought to these forums by a mechanical problem with one of my bikes. I'm 18, been riding bikes for 4 or 5 years now, Started on a DT 125, progressed to an XT 400 (my favourite bike) I rather classic bikes than newer ones, hoping to meet some helpful people who are also into the older Yamaha's. Cheers, and hoping to meet some of you guys!

Hey guys. I've recently hit a tree stump on my 1986 XT 400 and broken the gear shifter shaft (luckily I have another XT 400 for spares). The shaft has broken flush with the motor, so no way to reattach (weld etc). I have searched and searched for a way to change this, does anyone know how to change the shaft? The only way I can see is to drop the whole motor out and disassemble the top end to be able to even get to where I shifter shaft is, I've asked a few people and all they say is "You should be able to just slide it out" however it is not this simple. Any help at all would be appreciated, Cheers, Ricky.