ADVICE ON SCHOOL BIKE ENGINE


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cbx1260cc
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ADVICE ON SCHOOL BIKE ENGINE

Post by cbx1260cc »

If you came into possession of a school bike motor and removed the valve cover to ensure all parts / pieces were accounted for and in the correct location.

After ensuring Valve clearances are within spec.

Would you go deeper into the engine and do additional maintenance before install into a new frame?

First thing that comes to mind is--New Valve Guide Seals.

Yes or No?

Thank you for the courtesy of a reply

Regards

Ricardo

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herdygerdy
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Re: ADVICE ON SCHOOL BIKE ENGINE

Post by herdygerdy »

Years ago I went to Hawaii on hols and took a side trip to an island to help a friend put together a school bike Prolink engine. Admittedly, it came in boxes and had been stripped down to the crankcases (ie; cases were still together, cylinders, head etc removed.).

Discovered all sorts of odd-ball things, including some of the valve spring seating washers were missing. We managed to futz our way around all the issues found and got it back together and running-ish in a weekend, albeit with some issues including a flakey ignition coil.

Given the valve stem seals are heading for 40 years old now, IMHO to not replace them while you have the opportunity makes no sense at all. OTH, these engines probably did not do many (if any) heat cycles, so you may be OK. If it was mine I would though. It also gives you the opportunity to check the bores for damage/rust (ours were pretty manky) and maybe put a set of rings in it 'while you are down there'.

A lot depends on what you want to do with the bike long term. A final word of caution is that there is no way of knowing just how far down the engine had been pulled and put back together by kids with far more ambition than skill and maybe not much supervision.

Yes, you just might be able to do the shims, pop the lid back on and all is well. Then again, perhaps not. As Clint Eastwood put it so very well...."Are ya feelin' lucky, punk?"

Keep us posted on what you decide and enjoy the journey.

Cheers...Tony
Last edited by herdygerdy on Fri Apr 27, 2018 8:18 pm, edited 1 time in total.

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wyly
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Re: ADVICE ON SCHOOL BIKE ENGINE

Post by wyly »

yup, when in doubt tear it down...my engine was supposedly rebuilt by an experienced professional, the mechanic doing the rebuild now found four bent rods :shock: ...
CBX a work in progress, still improving...GS1150EFE completed and awaiting modifications.....RD350, remnants in boxes scattered throughout the garage

cbx1260cc
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Re: ADVICE ON SCHOOL BIKE ENGINE

Post by cbx1260cc »

Thank you for the courtesy of your input and the invaluable advice.

The best course of action seems to disassemble to check EVERYTHING before first start up.

Better to do it now than have issues later on down the road.

Thank you again for the advice.

Best to all

Ricardo

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herdygerdy
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Re: ADVICE ON SCHOOL BIKE ENGINE

Post by herdygerdy »

Hi Ricardo,

Great, it sounds like a good plan. Better to just 'know' it's right as you are cruisin' down the road rather than have it always playing on the back of your mind "wondering if..."

We are here to help you on that journey, and lets hope when you open 'er up, all is well.

Even if nothing untoward is found, It's a good opportunity to open up all the oil gallerys and get them surgically clean.

Be sure to time the notch (IIRC) in the primary jack shaft to the crankshaft correctly when reinstalling the primary chain, covered pretty well in the FSM. Many overlook this with dire consequences (bike won't start).

Don't rush it, be scrupulously clean, replace all seals where possible, ask here if unsure and you will be rewarded with a sweet running and very reliable ride.

Enjoy the journey.

Cheers...Tony

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wyly
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Re: ADVICE ON SCHOOL BIKE ENGINE

Post by wyly »

I asked the mechanic rebuilding my engine he said he worked on Cbx school bike when he was in school...he said absolutely tear it down because that was exactly what was done by numerous times by students, apparently over torqued/stripped bolts are common
CBX a work in progress, still improving...GS1150EFE completed and awaiting modifications.....RD350, remnants in boxes scattered throughout the garage

cbx1260cc
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Re: ADVICE ON SCHOOL BIKE ENGINE

Post by cbx1260cc »

Again a HUGE THANK YOU for the helpful input / advice.

Regards

Ricardo

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Re: ADVICE ON SCHOOL BIKE ENGINE

Post by daves79x »

Ricardo: Can you tell at all if there are signs the engine has been opened up? You should be able to tell if the valve cover has ever been off, for starters. Some of these engines were never touched. I had one such. Did the normal checks and it fired up and ran like it should have.

If kids had been into it, it would be very obvious right away and you would see cam caps backwards, missing dowels, caps in the wrong place, clear evidence that the head was off/cases split. There would be tell-tale wrench marks on everything. If you find none of this, I'd go ahead and service it as normal and run it.

Dave

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Re: ADVICE ON SCHOOL BIKE ENGINE

Post by tevan »

daves79x wrote:Ricardo: Can you tell at all if there are signs the engine has been opened up? You should be able to tell if the valve cover has ever been off, for starters. Some of these engines were never touched. I had one such. Did the normal checks and it fired up and ran like it should have.

If kids had been into it, it would be very obvious right away and you would see cam caps backwards, missing dowels, caps in the wrong place, clear evidence that the head was off/cases split. There would be tell-tale wrench marks on everything. If you find none of this, I'd go ahead and service it as normal and run it.

Dave
Dave I believe I sold him that engine about a year ago. I took valve cover off and looked everything over myself. I even went thru the valves and all were perfect. None of the fasteners were messed up and I don’t think that motor was ever apart. I am with you I would run it. I sold it without carbs of course.

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