Author Topic: motor rebuild thread (Read 33013 times)

Jerry Hall · « **Reply #60 on:** June 23, 2014, 11:45:19 AM »

Quote from: udontknowme;37285

aftermarket crank failures seem to be so common anymore that i hardly pay attention but i seen this one today. bearing seized up. he got off lucky and wont need a new set of cases http://www.thumpertalk.com/topic/1091833-2001-kx250-seized-connecting-rod/

It is sad to see the number of my customers that are willing to gamble against the odds on the aftermarket cranks and rod kits vs OEM parts when it comes to rebuilding a lower end.

Is another $100.00 or so on OEM pats on a lower end rebuild really worth the gamble especially the cost of replacing all of the other parts that get taken out when a crank fails?

Until one experiences and looses when they gamble on these substandard parts themselves, they will finally understand what we see on a weekly basis.

kidder86 · « **Reply #61 on:** June 25, 2014, 03:41:55 PM »

got the motor fired up. initially had 180 psi compression, ran for 20 min just idling. noticed there was water leaking out the weeping hole on the clutch cover. fixed that with a pump seal. put it back together, let it idle for 5 min then all of a sudden started reving real high, with no throttle input, the kill switch did nothing as did removing the plug cap, shut the gas off and it eventually died. checked compression after and its at 210 psi. im running 91 octane shell gas which has no ethanol. prob need race gas, wonder why this didn't happen the first time I ran the bike, or did I develop an air leak somewhere?

kidder86 · « **Reply #62 on:** June 29, 2014, 09:51:23 AM »

im going to build a leak down tester and check for an air leak. prob whats causing this

F-Red · « **Reply #63 on:** June 29, 2014, 10:44:55 AM »

It is one of the easiest tests, to perform. And will catch, possible issues. Good luck!

kidder86 · « **Reply #64 on:** July 04, 2014, 11:11:27 AM »

built a leak tester and found bubbles coming from the centre gasket:( worst place ever, im going to try and tighten the bolts and hopefully that works. cant believe this happened, I put gasket sealer on there along with the gasket!!!

udontknowme · « **Reply #65 on:** July 04, 2014, 12:12:33 PM »

i wouldnt go above 7ftlb or you may strip the threads. 5-7ftlb is plenty. if it still leaks your better off taking it apart and find out the problem. maybe one of your dowles is not letting it slide together or possibly the crank isnt centered correct

xTHUNDERCATx · « **Reply #66 on:** July 04, 2014, 03:22:13 PM »

Quote from: udontknowme;38361

i wouldnt go above 7ftlb or you may strip the threads. 5-7ftlb is plenty. if it still leaks your better off taking it apart and find out the problem. maybe one of your dowles is not letting it slide together or possibly the crank isnt centered correct

If I remember right the base nuts were suppose to be torqued to 30ish ftlbs.

udontknowme · « **Reply #67 on:** July 04, 2014, 05:26:24 PM »

right but the way i understood is the center gasket was leaking and he was tightening all the small bolts holding the cases together

Jerry Hall · « **Reply #68 on:** July 04, 2014, 06:25:52 PM »

Quote from: kidder86;38359

built a leak tester and found bubbles coming from the centre gasket:( worst place ever, im going to try and tighten the bolts and hopefully that works. cant believe this happened, I put gasket sealer on there along with the gasket!!!

If the engine has ever broken a piston or had a rod bearing failure there is a good chance the the mating surfaces of the cases that surround the crank shaft may be damaged. We are constantly repairing these surfaces.

A piece of broken piston will try to pass between the cases and crank. The piston pieces are usually thicker than the space. The cases will bend or crack when this happens. Checking the cases for flatness should have been part of a routine rebuild. We cannot assume anything is OK on these old machines. Everything has to be checked, that is why it is so expensive to have it done right.

kidder86 · « **Reply #69 on:** July 04, 2014, 07:24:57 PM »

didn't appear to be any damage to the cases. other than what's been posted and that wouldn't cause this problem. it was an aftermarket (winderosa) gasket. next gasket is going to be a Honda one

udontknowme · « **Reply #70 on:** July 05, 2014, 01:07:06 AM »

saved a few bucks initually but have to take it apart and get a new gasket. cost more in the end and alittle grief im sure :excitement:

GO OVRIT · « **Reply #71 on:** July 05, 2014, 09:13:47 AM »

Thats too bad. It's never fun redoing what you just did. That's why most on here preach OEM. The good thing is that you caught it before it ruined anything else.

kidder86 · « **Reply #72 on:** July 10, 2014, 12:29:59 PM »

tightened up all the case bolts to 12 Nm, most moved a bit. pressure test seems good. put 10psi and it had dropped less than 1 psi after 45 min. this sounds good to me. glad I didn't have to take it apart again.

JesseA420 · « **Reply #73 on:** July 10, 2014, 01:54:13 PM »

Quote from: kidder86;37101

as well as a boyseen reed valve, don't want to risk a broken intake boot ever.

worried about intake air leak lean condition, yet refuses to take professional builders advice on using a grenade for a connecting rod

o it wont be the last time you have to take it apart. it may even take itself apart for you.

udontknowme · « **Reply #74 on:** July 10, 2014, 09:10:07 PM »

it was mentioned several times already on the previous pages about the aftermarket rod stuff. im sure he dont need reminded anymore