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JR_TRX

Broken engine bolts top end

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Anyone know a trick to get the broken bolts out? The two long bolts and the two bolts next to the cam. 4 bolts total broke on the threads. Changing timing chain. Pretty depressed. 

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I believe you have a 300 Fourtrax , are the  bolts that  broke in this pic 

 

image.png

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Just now, Fishfiles said:

I believe you have a 300 Fourtrax , are the  bolts that  broke in this pic 

 

image.png

Yes.

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1 hour ago, Fishfiles said:

I believe you have a 300 Fourtrax , are the  bolts that  broke in this pic 

 

image.png

Apologies. Both 34’s and both 35’s.

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I would take care to drill right thru the middle of the broken bolts with a 5.2 mm bit , then run a 6 mm tap thru the hole 

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I would take it to a machine shop. Those bolts are a harder material then the cast aluminum the cylinder head and jug are made of and your drill will walk off and end up crooked. Any machine shop will use a drill press and center it perfectly. Drill and tap it to the next size and put a heli coil in it. My .02

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If you are going to spend the money for a machine shop to do the  work , I would just buy a good used head 

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Around where i am it will cost 25 bucks a bolt? I know other places its different. But i used head brings a whole laundry list of other possible problems doesnt it? Never looked at utility quad head prices but sport quad heads are around 200 dollars used. Seems aggressive to me?

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The 2 shorter bolts go in the head, the other 2 go down to the block/crankcase. The whole top end needs to come off to get to the outer 2. If your good with a welder most of the time you can just build them up a little, weld a nut to them and they come out. I've learned many, many years ago to apply very slow and steady pressure to those bolts until they break loose. Even then you will loose sometimes.

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Posted (edited)

Yeah I figured I need to go back into the whole top. Imma pick up some left handed bits today. I have a lil 110 welder. Order some used bolts as well. Hopefully they are what the pic shows. Think I’m about to learn some patience the hard way. When I took the top end apart the first time, I took my time on the bolts and then torqued them back to specs. Got in too much of a hurry this time. Frustrating… 

Edited by JR_TRX

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Check out Chromatron welding rods for removing broken studs 

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Really don’t wanna do that again. Bolt extractors. 

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