Need opinions

M

mcv80

New Member
Hey all,
So i have a 72 cb500 they i have been in the process of rebuilding and making a cafe bike well over the winter I figured it would be a good time to rebuild the engine. It was burning oil heavily and had seen better days. Well its gonna cost way over my budget right now to do the through rebuild that I have discovered its gonna need. In the mean time I still wanna be able to ride so I have a chance to pick up a 01 shadow 750 engine, running condition, no leaks, good compression, low miles for free from a friend and have debating on swapping it out with the 500 till its rebuilt to the potential I want it to be. It looks like it should fit without heavy modding and I have the fab equipment to make any changes necessary to make it work. Just give me your thoughts on it. All will be taken into consideration.
Thank you,
Tom
 
Hard to know how valid this thought is without actually seeing the condition of your CB500 engine, but maybe you should just throw a set of rings in it and ride it another season.
 
Without seeing both,it's hard to say, but I would expect that fitting another engine will burn through more time and $ than rebuilding the 500.

How bad is the 500 motor and what really needs to be done? If the pistons are OK to use i.e. not badly scored and close enough to spec, I'd reuse them in a pinch (with new rings) and replace them next season. If they are in a bad way, they have to be replaced and the barrels rebored.

Valve guide oil seals a bit of a pain to replace IIRC, but not impossible.

What does the motor need?
 
You should do a leak-down test to see where the leak is (valves, guides or rings).

Yeah, I agree with others. Fitting a Vtwin Shadow motor to a 4 inline frame is going to be pretty custom (read- time & money), not to mention alignment issues with the chain line, mounting the exhaust, etc.
 
Funny thing is, I was thinking CB500T and not CB500F. Even easier to work on but 4 of everything to replace. :-(
 
You could probably get the '605' kit (really 591cc) cheaper than rebuilding as stock, depends on price of boring.
The other alternative is, as already mentioned, throw some rings and valve guide seals in it.
If you have the required tools it can easily be done in a weekend (I've done my 550f in about 4 hrs)
 
The four is easier than a twin? I got turned off from fours because it was "four of everything". Twins are the most I would work on because of their simplicity compared to fours. Maybe the twin 500 is a twin cam, four valve? I know the four is a sohc 2 valve. But nothing sounds as smooth as a well tuned four.
 
Thank you for all of the reply's. Everything helps. Expense wise for swapping it wouldn't be bad as I have the entire bike to swap whatever I need over. I did some quick measurements with alignment and space and it should fit in theory. I do auto restorations and custom fab hot rod chassis as a side job and am a tool & die maker apprentice by day. As far as the 500 engine. the rings and bores are smoked. Will need a overbore, new pistons and etc. The valve guides are worn. Intake and exhaust. Needs new clutch steels and frictions and springs. Primary chain should be replaced at this point. So its no easy fix unfortunately. Was just curious to know if anyone else had done something similar or if I was breaking the code of the sohc 4 society haha. Well thank you all again for the opinions and if any one has any inspiration pictures the wanna share or any ideas they wanna voice. Please feel free.

Tom
 
Pistons and rings - get a cheap big bore kit
Worn guides - that's not a cheap one to fix and require the guides to be replaced and valve seats to be cut.

What about a replacement motor that has low miles? I realize they are all old by now but maybe a low mileage CB550 or 650 might be a good swap in.

Codes, like laws, are for those that can't think for themselves and are made to be broken (or bent) - that's not an exact quote but I'm sure someone said it.
 
yeah I have been looking into 550s and 650s but I have got this whole shadow for the most part just sitting around and figured why not. I highly agree with breaking the codes. I cant leave anything alone. All about putting your own twist on things. If I do end up doing this I will make a project blog for sure so everyone can see.
 
Show us some pictures, I've never seen worn out steel plates on a 500/550 (106,000 miles on mine)
You did the measurements correctly, particularly valve guides?

BTW, don't mention it on SOHC4.net ;D
 
I don't have any pictures of it apart but the steels had heat spots in them from the severe slippage. Yeah I would be shunned forever if mentioned over there. The valve guides I measured with a ball mic and I also did free play measured off of the valve head.
 
If the steels are in spec, just rub them down on 600 grade wet and dry.

How much play was in those guides? They don't usually wear if they are the OEM guides. Bronze aftermarket on the other had wear out pretty fast. IIRC Honda guides are sintered cast or steel and last forever - usually.
 
That shadow motor: what capacity is it and does it come with carb/efi and all the electronics needed to hook it up or is that in addition to the low cost of entry.

Hey. Maybe it's time for another Frankenbike and push the original motor into the pool of spare parts out there in fleabay land.
 
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