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Top End Rebuild Question

Posted: 03 Dec 2007, 21:46
by scrubs
Got my barrel back today after tuning and replating and looks pretty good, My only niggle is - if the valve shuts totally it jams a little so makes it difficult twist to arm to re-open, like its wedged. Since it should be running not totally closed on tick over i'm hoping this won't be a problem. Anyways if all goes well I'm gonna attempt to put her back together tommorrow depending on how much time I get. My question is how important is it to let the gasket sealant settle etc? I know it's suggested leaving it 24 hours, is this a necessity? Will I naff it up If I start the bike up as soon as I get everything torqued down?

Re: Top End Rebuild Question

Posted: 03 Dec 2007, 22:03
by Gwyn
[b]scrubs :[/b]
> Got my barrel back today after tuning and replating and looks pretty good,
> My only niggle is - if the valve shuts totally it jams a little so makes it
> difficult twist to arm to re-open, like its wedged. Since it should be running
> not totally closed on tick over i'm hoping this won't be a problem. Anyways
> if all goes well I'm gonna attempt to put her back together tommorrow depending
> on how much time I get. My question is how important is it to let the gasket
> sealant settle etc? I know it's suggested leaving it 24 hours, is this a necessity?
> Will I naff it up If I start the bike up as soon as I get everything torqued
> down?

Scrub. Dont hold me to this, but i'm sure, after a rebore, you have to file the powervalve so it moves freely :)

Posted: 03 Dec 2007, 22:13
by scrubs
Cheers Gwyn, I did hear something about filing the valve but thought
that this was so it cleared the barrel so the piston could fit in.
Someone will know :lol:

Posted: 03 Dec 2007, 22:28
by knackeredMk1
The main reason for filing the powervalve is to allow clearance when reboring. I don't think this should be a problem in that you are replating. Unless you have gone for a bigger piston?

The powervalve on my Mk1 sticks a little at the end of its travel (fully closed) but I think this is because of digging into the soft aluminium of the barrel. I think that just a gentle touch with the file to both surfaces will clean things up - but I haven't tried it yet.

I would try this. Mostly on the barrel to remove any burring if that is what's present in your case.

Posted: 09 Dec 2007, 17:07
by scrubs
Cheers Knackered,

Got everything back together today, Just started her up and the bikes
revving its nuts off not wide open but about half revs.

No cables sticking.

Any ideas?

Posted: 09 Dec 2007, 18:41
by Eddie Evans
[b]scrubs :[/b]
> Cheers Knackered,
>
> Got everything back together today, Just started her up and the bikes
> revving its nuts off not wide open but about half revs.
>
> No cables sticking.
>
> Any ideas?
Check that the slide is seating in the carb, also turn the ldle screw to see if that makes any differance.

Posted: 09 Dec 2007, 23:38
by andypugh
[b]scrubs :[/b]

> Got everything back together today, Just started her up and the bikes
> revving its nuts off not wide open but about half revs.

Air leak round the carb rubbers or reed block? Try squirting it all with WD40. If there is a leak the WD40 will get sucked in and the engine note will change.

Posted: 10 Dec 2007, 13:30
by scrubs
Cheers lads, I'm not home till the weekend so I'll try it then,
Would it just be just 'intake' effected? I.e would an air leak post carb
(say at the exhaust) cause the same symptoms?

Also... this is a long shot but, I remember just before the engine seized I was hearing a rattling sound coming from what sounded like the
left hand crank case side. After I put the new piston in the sound is still there it sounds like a bag of poo really noticeable, hard to describe the sound kind of rattling/scraping with odd knock. Could something have broke of and dropped deeper in to the engine? :(

Re: Top End Rebuild Question

Posted: 19 Dec 2007, 14:43
by jipé
Where did you have your barrel tuned and replated ? I am interested because I am leaving in Madagascar, and had the cylinder of my MK1 resleeved in a local workshop. But now the byke is wasting 10 liters per 100 kms, oil consumption has doubled as well, the engine lost much of its former power, and tends to overheat in Antananarivo's traffic Jams. Therefore I am afraid I'll have to reopen the engine and do something with the sleeve.

Jipé