Anyone ever replace lower engine case ?

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pearly427
Posts: 33
Joined: Sat Jul 20, 2019 2:39 am
Location: U.S.

Anyone ever replace lower engine case ?

Post by pearly427 »

Hello, I have 2 questions concerning my 75- 550 engine problem. I’m having problems starting my bike because the 2 holes that hold the idler gear pivot are not holding the pivot securely into place. One hole has 2 little cracks because someone didn’t use thread lock. I tried retightening the two Phillip beveled screws with thread sealant but it came loose again. The only way, I see fixing it would be replacing the lower engine case where the one hole that has 2 cracks are replaced.

Question 1: Does anyone know for sure, if I can replace the lower engine case by turning the engine over once removed from bike and just replace lower engine case ? Leaving all transmission parts intact. No other jobs of removing anything else ? I just want to replace the lower engine case to replace the two holes that hold the idler gear pivot mechanism. I don’t see any other way to repair the one hole that has 2 small cracks in the aluminum ? The cracks are causing the hole 2 expand under torque.

Question 2: Can I temporarily remove the idler gear all together and just use the kick starter only ? When I reassembled the bike after an attempt to fix it. The kick starter would not work ? The electric starter worked fine, until the 2 screws came loose again. Now the kick starter turns the actual clutch basket. But, will not turn the crank.
barney01
Posts: 3118
Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: Anyone ever replace lower engine case ?

Post by barney01 »

The simple answer to question 1 is no. It has to be a complete strip down to replace the crankcase's I'm afraid :(
It is also better to get a complete set of cases as in the factory when made the holes are drilled together. If you just buy a lower case there may be alignment issues.
With regards to question 2 I think that the clutch basket has not located properly with the primary drive gear on the end of the crankshaft. I've never tried it but I can't see any reason why you can't run the bike without the starter idler gear, as long as you remove all the parts.
NO SMOKE .......NO POKE
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Alan H
Posts: 12104
Joined: Fri Aug 05, 2011 6:38 am
Location: Wombwell, Republic of South Yorkshire

Re: Anyone ever replace lower engine case ?

Post by Alan H »

I have a set of 550B cases 'spare' if you need some.
(They are actually at Baz's, having had all the internals removed to go in the A motor who's gearbox was knackered.)
I have other sets if those are the wrong year.
Proof that four strokes are over complicated
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canaletto5
Posts: 5228
Joined: Tue Jul 23, 2013 8:43 pm
Location: Derbyshire

Re: Anyone ever replace lower engine case ?

Post by canaletto5 »

Alan H wrote:I have a set of 550B cases 'spare' if you need some.
(They are actually at Baz's, having had all the internals removed to go in the A motor who's gearbox was knackered.)
I have other sets if those are the wrong year.
Postage might be a bit steep
pearly427
Posts: 33
Joined: Sat Jul 20, 2019 2:39 am
Location: U.S.

Re: Anyone ever replace lower engine case ?

Post by pearly427 »

Ok, I fixed the kick starter. I made the mistake of trying to adjust the clutch without the clutch cover on. That’s why the kicker wouldn’t work. I removed the clutch for the fourth time and even though I don’t trust my idle gear repair long term. To my surprise the idler is firm in its place with no wiggle. But, I removed the gear so no further damage occurs. For some unknown reason, I have a lot of wear on the starter gear, but no wear on idler gear ? i tried wiggling the starter from clutch side and it doesn’t move ? These starters can’t be found in the U.S. and people are wanting $350 for them when they are available. That’s not gonna happen, lol ! I ll push it up Mt. Everest and drift start it back down first, ha ha !
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