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Had this problem on my XT550. Firstly check the pipe between the cards is ok and not split, this is a balance pipe from memory and mine was perished. I would then check for dirt etc in carb, as an easy fix. (apart from getting them of the rubbers!) Worst case - which mine was the CDI unit was failing. (Was ok on part throttle but major misfire from around 3500 rpm on. Replaced it and fixed completely. Hope its just dirt! Nick

I've got an XT550 and had a similar problem. First thing to check is for an exhaust leak, particularly around where the downpipe fits into the exhaust. You can use high temp silicon to make the joint. For info mine had an aftermarket exhaust and the cutouts in the exhaust to put it over the downpipe where too long. When assembled there was a gap when the downpipe was pushed in. I made up a thin copper collar from sheet and wrapped that around then used the silicon. Second thing is to check for an air leak between the carbs into the inlet manifolds. They perish and then leak. Finally check if your carb has what is called a coasting enricher (looks like a cap screwed onto the left hand carb by, from memory, 2 screws). Under this is a diaphram, if this is damaged the valve does not work and allows fuel to be pulled through when you shut the throttle quickly, and this burns in the exhaust, hence backfire. Be careful if you remove the cap as it has a spring behind it! When I bought my bike it had carbs without this enricher on it, and even after fixing the leaks in the exhaust it still back fired badly. After changing them for a set with this on the problem has almost gone away. All big singles will back fire a little when shutting the throttle from high speed by the nature of the engine. If you cannot find the cover on the carb, or not sure drop me a note and I will take some pictures of mine to show you. Good luck! Nick

Not sure if it helps but my XT550 has a one way valve in the engine case to stop oil draining back into the cases (it has an oil tank in the frame so not the same set up). It might be worth looking to see if the manual shows you have a similar valve? - it is a small rubber seat with a spring and ball bearing in it Nick

Let me know what you need, as have a load of parts from when I restored mine. Also have a parts list/diagrams if it helps. Let me know Nick

Most parts are available depending what you need from Yamaha. Aftermarket parts are available but not as common as XT600. As for smoking is it just on starting/cold, or all the time? Nick

Haven't got them, but got loads of other parts. Let me know if you need any others - are you in the UK? Regards Nick

Does anyone know which part in the wemoto on line website fits either?

Does anyone know if Yamaha part number 395-83980-00 (front brake switch) fits a 1986 XT600 front master cylinder? Thanks Nick

Tank is built into the frame itself as an integral part, i.e. the two top halves of the frame welded together and the headstock welded to them, so is not removeable, and has three pipe connection and the oil filler cap. If the sand blaster does not seal it properly and sand gets in it will be impossible to flush it out 100% and hence minus 1 engine!

I am restoring an XT550, which has a dry sump and the oil tank in the frame. I need to paint the frame, and previously had bikes plastic coated, but am worried that sand blasting before coating will get in the frame and hence into the oil. Has anyone successfully blasted/plastic coated a similar frame, or if not can recommend a red colour paint to paint it with instead? Thanks Nick

Can any one let me know the minimum disc thickness for the front disc of a 1985 XT600? Thanks Nick

Can anyone tell me if all the front wheels off XT600s are interchangeable, or what the differences are, as I want to fit one to an XT600 front end from circa 1985 I am putting on my XT550, and have seen one for sale but the seller does not know which XT600 model it is from. Thanks Nick

No problem, will try to copy it tomorrow and send it. Do you need any other pages whilst I am at it? Nick

Ross - I have just restored a 1981 XT250G and have the genuine Yamaha manual. Its black and white text but shows the colour codes, and I can copy the diagrams, scan and e-mail to you if you want if you let me have your e-mail address. Nick

Just ordered a new RH mirror from the USA for my XT250G 1980 to finsh the restoration project and it has arrived, is the right part number, but has what appears to be an M8 LH thread, but the handlebar clamp seems to be M10 - not sure if LH or RH. Does anyone know if there is an insert missing from the clamp as the other side appears to be the same size and I don't want to order the other hand and find that doesn't fit either. Thanks Nick