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Yamaha XS250


chrisadams810
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The chain is probably just hanging down in the sump at the moment, I wouldn't worry about that till you get the replacement cam shaft cog. But if you shine a torch down through the head and into the sump there is a chance you can see the chain and sprocket. You could, if your brave, is hold the chain over a screwdriver shaft and tension it and hit the starter button, won't do any harm and will put your mind at ease about it being attached and working..

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So I've removed the cylinder head cover and removed the cam. Peered down to check the chain guides. The sprocket has wedged itself in the depths of the engine and it won't budge. I've found one bolt under a valve spring but not the other. It's time to strip. 

It's alright though. I'm enjoying the process. I don't get a great deal of time on the bike (it was supposed to be a quick starting fault rectify) but when I do get the spanners out I've enjoyed seeing how well these bikes seem to be put together. 

Now I can reassure myself that when it's all back together it'll run properly as I have my doubts about the Po's workmanship. 

On 11/10/2017 at 10:14 PM, drewpy said:

crank sprocket is part of the crank, so the PO couldn't of removed that

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All fragments of the sprocket now removed after removing the head. The last small piece came out through the plate and gauze underneath the block. Thanks for the help and patience. Just need to put it all back together now. 

 

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No the camshaft was there. One of the sprocket bolts retrieved has a badly stripped thread. I think the bolts weren't tight enough. The sprocket has been vibrating and slapping against the casing and shattered. 

A little concerning is from what I can see a slightly damaged tooth in the crank gear. 

 

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A little advice and input might be needed. Having put the sprocket and cam in with it set for 'LT', cam pin in air and the lines on the sprocket horizontal I've attempted to fit the sprocket bolts. 

Two problems. One is when fitting the sprocket bolt and then turning the engine I'm pretty sure the chain is jumping on the crank sprocket. So the cam isn't actually turning. Only when I provide it with assistance. Is this because the tension blades aren't in yet or because the sprocket teeth might be too damaged. I noticed some damage on the teeth but clearly shrugged it off and will probably pay for it now. 

Secondly I'm pretty sure the cam thread is damaged. As a) I found one of the original bolts had a stripped thread and  the bolt is immediately tight. 

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you will have to provide some tension to the chain or it will jump.

 

if it does jump, just feed the chain around the cam sprocket till it lines up again

you may be a ble to retap the cam thread if the bolt sheard, only by looking will it be aparant

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36 minutes ago, drewpy said:

you will have to provide some tension to the chain or it will jump.

 

if it does jump, just feed the chain around the cam sprocket till it lines up again

you may be a ble to retap the cam thread if the bolt sheard, only by looking will it be aparant

Thanks I've played with the chain and seemed to have got it to turn. 

I've also found the spark plug thread to be not much better. So I'll be dealing with that next. I'm no whizz kid mechanic but boy was this bloke useless. 

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4 hours ago, chrisadams810 said:

Thanks I've played with the chain and seemed to have got it to turn. 

I've also found the spark plug thread to be not much better. So I'll be dealing with that next. I'm no whizz kid mechanic but boy was this bloke useless. 

use a timesert or helicoil for spark plug thread, in fact do both at the same time as it makes better engineering sense for the get go.

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  • 3 weeks later...
On 25/10/2017 at 4:33 PM, drewpy said:

Yesterday I rode the little 250 up the street yesterday. 

Sounds good! Just needs a bit of fine tuning to make her run better. 

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4 hours ago, chrisadams810 said:
On ‎25‎/‎10‎/‎2017 at 4:33 PM, drewpy said:

Yesterday I rode the little 250 up the street yesterday. 

Sounds good! Just needs a bit of fine tuning to make her run better. 

did I say that? :D

 

glad to know its working.

 

fine tuning makes the world of difference

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Whoops my bad!

Unfortunately my points must be earthing on the cover. Because with the cover off it runs. It does not with the cover on. 

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22 hours ago, chrisadams810 said:

Whoops my bad!

Unfortunately my points must be earthing on the cover. Because with the cover off it runs. It does not with the cover on. 

there were 2 types of cover, the larger one though was for the electronic ignition. and was a plain jane affair, the actual points ones look better as they have fins on.

 

may need to look at the route of the wiring in case its getting trapped

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Although not the complete reason why but it's lead me to purchase electronic ignition. 

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On 17/11/2017 at 4:28 PM, chrisadams810 said:

Although not the complete reason why but it's lead me to purchase electronic ignition. 

which one?

I got the Pamco from USA.

http://xs400ignition.com/

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The Newtronics kit from Yambits

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1 hour ago, chrisadams810 said:

The Newtronics kit from Yambits

|I had an old one, they are pretty good

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