Two Stroke Motocross
Two Stroke Motocross Forum => Technical => Topic started by: RedFoxCR on July 27, 2010, 12:40:19 PM
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Guys, i really need some advice. I was rebuilding my bike (1999 honda cr250r). After installing a new head gasket, i started tightening upper nuts, i've got six. One nut suddenly clicked and started rotating effortlessly. It was clear that the bolt is torn, but to compensate that i decided to tighten other 5 nuts stronger... but at once i tore one more bolt, the neighbor one. The cylinder started leaking with coolant althoug the compression was still fine. After unmounting the head, i saw that the upper halves of bolts are separated from the lower ones, still stuck in the cylinder... What can i do???? Will something like metal-epoxy glue help??? The cylinder is aluminium, the bolts and nuts are steel.
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It's too late now, but always use a torque wrench with head and cylinder bolts.
Is there any bolt at all sticking up where you could grab it with Vice grip pliers? You also may be able to use an EZ out type of tool since it sounds like you broke the bolts? A picture would help with advice.
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On the upside,where you were tightening them down it's not like they're seized in so they should come out easily.Like coop said,ez out,v grips or if you're lucky,a left hand drill bit.
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If you have enough threads for 2 nuts, you thread a nut on the bolt, then thread the 2nd nut tight against the 1st nut. Then use a vise grips on the bottom nut, lefty loosen. It works I did it last night in the dark, I use a old nut on the bottom.
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Thanks guys. Ijust managed to screw out one bolt fragment using a small drill and then something like left-side widening screw in the hole then. But another one still sits in the cylinder. We tried to repeat the trick, but it was unsuccessful. I got the very edge of the bolt with the drill, so i couldn't rotate the bolt. Maybe it's possible to destroy the rest of the bolt with a huge drill and then cut new tracks and screw a bigger bolt in?
Also tried a head gasket from soft steel, but i'm afraid of tightening now, so i tightened it lightly and the goddamn coolant got into engine.
I also got something like thick black carton enforced with steel net inside. Maybe i should use this? Thanks in advance.
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Take it to a machine shop and get them to remove the broken stud.
It's cheaper then ruining your engine.
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Black stuff suddenly blew with awful noise. Tried installing stock steel gasket, covering it with some red ABRO gasket maker. (343 degrees Caelcium). It has no signs of leaking or compression loss. I would say the compression is TOO good. Another problem is that gasket maker can flatten, expand and half-close coolant holes in the gasket. I have some light detonation in mid-range and the engine heats very quickly, although it can be my imagination. Maybe it's good to disconnnect all coolant hoses and pump some water through the head???
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I think it's good to fix it properly. ;)
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I think it's good to fix it properly. ;)
Exactly. This is something you definitely don't want to be jerry rigging.
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It's never gonna seal properly without all the head studs.
You need force spread evenly round the head to get a proper seal.
And yeah if it's starting to detonate and get hot then chances are you might've blocked some holes.
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Why do people ask for advice and not listen? :-X
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Why do people ask for advice and not listen? :-X
I agree. Lots of people ask advice and when it's not what they wanted to hear they either argue or ignore you totally. That happens a lot on thumpertalk.
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Why do people ask for advice and not listen? :-X
I agree. Lots of people ask advice and when it's not what they wanted to hear they either argue or ignore you totally. That happens a lot on thumpertalk.
Yep, though most of the time it's kids on Thumpertalk that do that...
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I've long wondered the same thing.On one of the other sites I'm on,someone would get on asking for advice and once given,it usually went unheeded.One of the guys on that site is the bike dealer I deal with and he'd give the guy the cure(which I thought was good of him given his business depends on fixing customers stuff for $$) and get no response.
In the meantime,some kid would get on and say "yeah man,my cousins brothers uncles son had the problem and it was the spark plug" The guy would jump on that and say"thanks man,I'll try that"
On the other hand,it may be that sometimes they're looking for the easy way out or just aren't mechanical enough to do the proper repair.I don't know.
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Any status updates on this issue RedFox?
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Guys, i'm really sorry for not logging on for so long. My bad. I'm really grateful for every single bit of information you gave. Thaks a lot!!!
So, the situation is
I managed to screw out one bolt fragment drilling a small hole at the center of it and screwing there a special tool with right threads. However that didn't work out with the second one. I missed the center and made a hole half in bolt, half in cylinder meat. Screwing this shit out is just impossible, so i reassembled it with five bolts. O course the distribution of the force isn't very even and i have coolant slightly spraying outta head. However that doesn get into the bore cause the compression is still perfect.
MAybe it's possible to drill the whole bolt w ten millimetter drill (the bolt is 8mm diameter) and cut new big threads&
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At this point, I pull it off, and go to a machinist. They have the tools and equipment to fix the problem. Nothing like the right tool for the job.
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I speak from experience please for the love of your engine block go to a machine shop, depending on how bad its screwed up it will only cost you about 30 bucks.
Btw as others have said make sure you use a torque wrench next time, head and cylinder bolts are probably the most important ones on your whole bike.