Topic: Seeking advice on buying a blown/siezed engine

[DedHed]

I found a honey hole of a "Experienced motorcycle parts yard" and thinking about the following.

I have never torn into any engine bigger than my parents Briggs and Stratton in 1979.... I still owe them for a mower..... I am considering buying a 1970 - 1976 SOCH4 engine preferably a 750 K motor. The purpose of this motor will be no more than an educational exercise for me. I would much rather go through the learning process on a motor that won't run rather than my perfectly running 74 750 K4. The ultimate goal would be to have this motor running again with out much $$ investment, the time (Labor) to get it running is not that big of a deal to me, See; learning experience....

What would one expect to pay for a siezed or blown motor, I think the only criteria to determine if blown or siezed  will be putting a wrench on the crank or trying kick it over. I will also, if able, take a peak under the valve tappets, intakes, oil tank etc... To get the best of the worst.....
 
From reading the forum.. I gather a decent engine can be found anywhere between $250 and $400. depending on many factors.... I'm thinking $100??? I understand that it will cost whatever I'm willing to pay, but I am looking for some guidence from the brain-trust here....

Thanks in advance,
Phil

[Stev-o]

I've seen used 750 motors in various condition selling for $100 - $300. Thing is, shipping is expensive so you really need to find one local or it makes it cost prohibitive.
And a seized engine normally describes a mech failure while a "stuck" motor can be the piston rings rusted to the cylinder wall from years of sitting. (I have "unstuck" one). 
I think what you havein mind is a great idea.  Are you aware of the 836 big bore kits on eBay for $119?

[DedHed]

I have not checked the 836 bore kits... Yet!

This motorcycle junyard is FILLED with sohc4 motors.... I think I'll be best satisfied if I keep my expectations clear. Learning  exercise, If I get it running again, that will simply be a bonus. If I do get it running... I get to spend more on a frame, wheels, etc.... Perhaps take an old bike and build it up to a "Rat" bike, instead of taking a perfectly good bike and disassembling  to a rat bike, I would be assembling up. It makes sense to me....

Thanks, if I do, do this. I will document for my own sake, and perhaps "start a thread.... "Don't scrap that motor"...

Phil

[Stev-o]

Don't scrap those motors!  Rebuild reuse...

I have a couple motors that I plan to rebuild one day, and plan to buy this kit. Note: it is from Japan, not China.

http://www.ebay.com/itm/69-77-HONDA-CB750K-836cc-BIGBORE-PISTON-KIT-W-GASKET-/140697308917?pt=Motorcycles_Parts_Accessories&hash=item20c2368ef5&vxp=mtr#ht_1484wt_689

[MoMo]

Good learning idea and the inexpensive big bore kit would be a plus if the motor is stuck...Larry

[754]

 If the motors are out and you can check them, ie re & re the valvecover...look for one with big lumps and different springs...tell them you are trying to avoid a burnt-out cam bearings motor.. Take a look at the intake ports for porting too...

[Old Scrambler]

Like Minds!.........I have 11 motors in my stash........one is getting rebuilt with a little extra in the cam department.  I look for early motors and those with aftermarket allen heads because if all else fails, the early heads have more resale value and the allen heads often indicate someone may have added some internal 'goodies'.  I have paid less than $100 for stuck or damaged motors.......and I have a weakness for the black F2-3 motors because the cams and valves are in high demand.

[754]

 Always look at the serial # and for chaindamage to cases If you see any numbers ending in 44800 or lower PM me, if they look like this10999 or lower call me collect at 250-763-RACE... trying for a 6pack of  them motors...

[Stev-o]

Always look at the serial # and for chaindamage to cases

Good point 754. Ded - always check around the front sprocket for damage, you may have to scrape the dirt/grease away. The early motors were prone to case damage by broken drive chains.

[Brantley]

When I read "yard" in yr post it kinda makes me cringe. In my mind there're three kinds of bike in your classic outdoor, muddy, oil spilled boneyard: a) wrecked, b) blown up from abuse/ lack of maintenance, and c) "this stopped running fifteen years ago and I'm tired of looking at it in my yard/ car port/ shed so please haul it away for free". Try to build a rapport with the folks that own the joint so they are comfortable with you poking around on your own. It's a great idea, but be patient. Remember there are still a lot of old timers out there that don't do computers, only the local paper or trader paper. $100 seems about max to me in any condition that ain't running.