ANOTHER 750 REBUILD

Questions regarding the DR750

Re: ANOTHER 750 REBUILD

Postby BigBob » Tue Feb 05, 2013 4:03 pm

I`m afraid those rockers definitely look cream crackered mate, sorry to tell you that.
Cant see the condition of the camshaft, but I expect it`s also Donald Ducked.
Almost certainly the culprit is the blue gasket shite that the ham fisted halfwit used on the rocker box, and loads of excess will have made its way downstairs.
If you remove the fag packet sized sump cover you will almost certainly see an oil screen covered in it, which prevents sufficient oil getting to the top end.
Clean the screen thoroughly and then flush the engine with white spirit to remove any shite lurking anywhere.
The Suzuki Holy Books says to use 3 bond gasket for a reason, and you can see why.
Blue Hylomar is the spawn of the devil and is responsible for killing many a Big unfortunately.
Save a few quid on 3 bond and kill an engine..........what a great idea!
The bad news is you`ll need two new rockers at £69.34 each and a camshaft at £193.87 :o
CMSNL charge E58.50 X 2 and E188.50 plus extortionate postage.
There are old school people out there that can reprofile cam and rockers at sensible money
Good luck
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Re: ANOTHER 750 REBUILD

Postby spendango » Tue Feb 05, 2013 4:32 pm

I take it you have none for sale in your spares box then ?????? When you say flush the engine out , whats the best way to go about that , White spirit from the top poured down ? May try to get a second hand set of rockers and cam from fleabay .will sr42 800 stuff fit so i know what models to look at .cheers Mark :cry:
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Re: ANOTHER 750 REBUILD

Postby BigBob » Tue Feb 05, 2013 5:08 pm

Can`t help with spare cams or rockers unfortunately.
Send Lars a pm, as he machines all sorts of things and may be able to repair them.
I just fill up the engine with 5l of white spirit as you would with oil, and then undo the sump plug as you would normally.
If you use a clean receptacle and a tea strainer, you can flush through several times.
SR41/42 and 43 heads/cams/rockers are all pretty much the same.
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Re: ANOTHER 750 REBUILD

Postby spendango » Tue Feb 05, 2013 5:12 pm

A friend of mine rebuilds old nortons and sends his cams to "Newton cams " ever heard of them ?? The instant gasket shite was black probably still some sort of cheap shite ,plenty of oil up around there just wondeing did some TIT set the tappets to tight ?? :wtf:
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Re: ANOTHER 750 REBUILD

Postby nug » Tue Feb 05, 2013 6:49 pm

As Bob said Spen its most likely oil starvation to the top end. Maybe the cam oilways blocked or the followers have been mixed up. The cam journals look ok on the cam cover though so I wonder if the cover is the original ? Unlikely to be incorrect clearances tbh. If you buy a used cam then you need the matching rocker that are bedded in to match or you may get premature balding... sorry I mean wear. Cams can be welded & reground by the correct people if you can find one. You need a parts bike :tup:
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Re: ANOTHER 750 REBUILD

Postby spendango » Tue Feb 05, 2013 7:10 pm

My worry is I spend the money and there is a blockage will it happens again !!! I have the replacement oil seal for the inside cof the clutch casing ,isn"t that where the oil is forced up to feed the head ? Bob can i blow any of these oil ways out with an air line ,Where do the feeds come up at the head ? So nug you telling me it"s a cam and matching rockers needed .one without the other won"t do .Any more input would be a great help . :( Bike is ready to start building all i need is an engine LOL
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Re: ANOTHER 750 REBUILD

Postby nug » Tue Feb 05, 2013 9:13 pm

Its never good practice to mix worn parts like cam/valve train parts. One worn rocker has significantly more bedding in to do when faced with a worn cam. New parts are machined perfectly flat so need less bedding in. You should never swap the exhaust & inlet rockers when you strip the cam cover as this creates the same problem although many people do it without really thinking about it. Many years ago when the Ford 1.6 & 2.0 pinto engines where in everything, many people I knew would get a hot cam & chuck it in on the old followers (rockers), they would wonder why the cam only lasted a few thousand miles.This may be what happened on your bike Spen. Good idea to replace that crank seal as well :tup:
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Re: ANOTHER 750 REBUILD

Postby spendango » Thu Feb 07, 2013 2:08 pm

Ok some red bits :tup: before and after
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Re: ANOTHER 750 REBUILD

Postby H_Lime » Fri Feb 08, 2013 10:36 am

Looking good Spen :tup:
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Re: ANOTHER 750 REBUILD

Postby Longman » Fri Feb 08, 2013 6:35 pm

Looks good Spen,just got mine back from rebuilding. Great shade of red. It looked orange inside the bike shop and when outside, in dull light..............very red. :clap:
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