Topic: screwed

[KRONUS0100]

first..want to apologize if this is long.
problem................stripped stud threads for my 74 CB750.  On advice from few people and a "SUPER MECHANIC"  ( I now use that term loosely)...I drilled and tapped the head for  8mm studs.  8mm will not go thru the dammed cam towers..they have to be turned down to 6mm but keep the 8mm threads.  Cant find a machine shop to turn them down.
have looked at timeserts and gard zerts and helicoil and a few others.   way too cost prohibitive with the minimum number required to purchase.  So now I am screwed. I did drill an old trashed tower out to 8mm......not enuff room at the cam journal to be run safely...we are talking less than paper thin at the bolt hole to journal area....again...screwed.
Either I find some one to turn the bolts I have down to 6 mm so they go thru the towers, or I have to find a replacement head and scrap a otherwise perfectly good head.  More than a little bit pissed here.
any help much appreciated, and please dont rake me over the coals for this, about had it with this bike at this point.

[BrianAdair]

I had one cam tower bolt break on me and I drilled and tapped it for 8mm/6mm timesert.
I'll check and see where the guy I know that had the timesert kit gets his, thought he said the whole kit with serts and taps was around $50 to $65.

[BrianAdair]

this site has the kit with 5 serts for $59.00 and then the serts individually for $1.49 ea.

http://www.hrpworld.com/index.cfm?tpc=Time-Sert_Metric_Thread_Repair_Inserts&form_prod_id=5985&action=product

probably come out cheaper than the cost of a machine shop, most are $75 per hour and up around here.

[KRONUS0100]

cool.  thanks guys.  nice to know there are still decent folks in this world.  the one pplace i looked quoted 60 for the install kit w/o the inserts...minimum order was 350 plus inserts at 2.70 each.....friggin ridiculous.

[KRONUS0100]

#$%*...the timeserts wont work in the 6mm siex...require hole at .246 inches...just under 1/4 inch.  the hole is already 8mm....would still have to have the bolts turned down.

[754]

 You are not sunk yet. A few options..

 At times I have made up repair inderts, from steel or aluminum. You may have room in there to make one with 8mm OD and 6mm ID Installing them can be a bit tricky.
 Usually when I have done this, I have the part there, then fit the OD of insert fairly tight, rather than loose fit. To install, I usually neck down the piece, use a drill chuck to install(+red loctite), then snap it off and dress down the material, then chamfer. or you can screw slot it, to install. Often I use 7075 Aluminum for this as it is MUCH stronger than cast, but should have similar expansion rates.

 I need to know how deep the tapped portion is, and pitch of the 8mm thread. I could turn down a set of studs and rethread to 6mm or 1/4 inch.
 Look at options from 5/16 to 1/4 inch, the pitch may be close to the hole you tapped..

 This may be better in the Tricks & Tips section

[KRONUS0100]

hold that thought.................................may have an answer from EZ-LOK.   resonably priced for full kit and the few extra inserts.

[KRONUS0100]

UPDATE....................................bro is making me some inserts out of 10mm bolts.  he says gona use the good green loctite to put them in.  that stuff will need heat from a torch to come loose.

[754]

Why 10mm, I thought they were at 8mm??

 Just fit them snug to the 8mm threads..

[KRONUS0100]

I dont know why 10mm..................he has the head with him.

[754]

Here is my take, fit the made-up insert to the thread for a snug fit.. which is probably not going to happen with off the shelf stuff, there is always clearance.

 Get too big in there, you may as well weld them up. But as I suggested, a hard alum insert, is MUCH stronger than the original threads..

 Keep in mind that they cannot protrude above the surface.

[KRONUS0100]

UPDATE:
finally got out in barn for a bit.  solved my own problem by making my own inserts out of old 3/8-16 bolts.  drilled down thru the middle of them and threaded for the original 6mm tower bolts.  then cut them off to length needed.  best part....since the tap for these bolts required 5/16 drill, i did not have to redrill my head yet again.  I had allready drilled them for 8mm bolts which i found out i couldnt have turned down.  will get some pics if someoe reminds me how to post them.   WHEW!!

btw..................got tired of waiting on people and thier promises of getting it done for me.

[754]

 Hope you used red loctite.. Normal taps and fasteners can result in a rather loose fit..
 
 Hope its fixed now..