XS1b engine smoking badly!

[jhart]

Hey there, picked up a 1971 XS650 (XS1b) last summer and have been having trouble getting it started. When it does start (kick start only, although it does have an electric as well), it smokes horribly, more on the right side than the left. Compression on the right is ~190, Left is ~90psi. While changing the oil and oil filter for the first time today discovered metal shards in the old oil and on the filter. Adjusted the valves, timing and cam tensioner, as well as new battery and spark plugs, with no effect on startability or smoke (whitish smoke that smells of oil). Next step will be a leak-down test, but have to locate the equipment for that.

Any ideas as to where the problem lies?

 

[retiredgentleman]

Hey there, picked up a 1971 XS650 (XS1b) last summer and have been having trouble getting it started. When it does start (kick start only, although it does have an electric as well), it smokes horribly, more on the right side than the left. Compression on the right is ~190, Left is ~90psi. While changing the oil and oil filter for the first time today discovered metal shards in the old oil and on the filter. Adjusted the valves, timing and cam tensioner, as well as new battery and spark plugs, with no effect on startability or smoke (whitish smoke that smells of oil). Next step will be a leak-down test, but have to locate the equipment for that.

Any ideas as to where the problem lies?

No need for a leak down test. Engine internals are wornout; top-end re-build required. Replace all the usual components .................rings, valve seals, head gasket, camchain, front camchain guide, oil seals .................measure valve guides to see if they are worn and may also need replacing. Valves will need to be reground. Once apart measure cylinder bores and pistons to see if a rebore is needed.

 

[jhart]

Ok Retiredgentleman, so don't go and buy rings until I've established whether or not cylinders need to bored out? Thanks for the reply!

 

[retiredgentleman]

Ok Retiredgentleman, so don't go and buy rings until I've established whether or not cylinders need to bored out? Thanks for the reply!

Yes, don't buy any parts until you take the top end apart, and measure/inspect everything.

There are top end re-build threads...................use the google search in the upper left corner.

Get familiar with the Yamaha Service Manual, found on sites such as www.biker.net.

A Haynes or Clymer manual will be very useful.

 

[jhart]

Yes, don't buy any parts until you take the top end apart, and measure/inspect everything.

There are top end re-build threads...................use the google search in the upper left corner.

Get familiar with the Yamaha Service Manual, found on sites such as www.biker.net.

A Haynes or Clymer manual will be very useful.

Cool, thank you!

 

[angus67]

did you say your 1971 has electric start?

 

[jhart]

Yes angus67, it has an electric start which looks like a small brake lever, on the right side of the handlebar. It looks like it has an exhaust compression release as part of the assembly.

 

[NONclow]

Yes angus67, it has an electric start which looks like a small brake lever, on the right side of the handlebar. It looks like it has an exhaust compression release as part of the assembly.

Hmmmm sounds like an XS2 to me....

+3 on what RG said about the usual suspects. The motor's tired... you will be (after the rebuild ). Time to get greasy

 

[neanderthal]

yeah 72 was the first year the electric starter was added.

 

[XSLeo]

What I might suggest is checking your frame and engine numbers against one of the charts that list the model year by frame numbers. You will find such a chart in the XS650 TECH section.
It may have a build date of 71 but that don't make it a 71.
190 psi? Sounds a bit high on that side. the stock specs call for 145psi minimum on a good engine. often run 150-165 psi. With Mike's 750 kit I get around 190 psi. You might find a lot of carbon build up on the right side, probably from all the oil burning.
Leo

 

[gggGary]

A heads up fleabayer crusinimage is now offering 2nd oversize piston and ring sets for the 256 engines. $100