XL500 R engine question

[adam.m]

Anyone know anything about the XL500R donk ?
The 2 long bolts, seen in the pic, go down through the head into the cylinder, and hold the bracket for the decomp.
On mine, the bolts dont do up, they are not broken, but are either not long enough, or the threads are stripped.
Im wondering how critical it is to have these bolts done up ?

[smed]

http://www.powersportspro.com/pages/OemParts?aribrand=HOM#/Honda/XL500R_A_(82)_MOTORCYCLE%2c_JPN%2c_VIN%23_JH2PD020-CM000032_TO_JH2PD020-CM009868/CYLINDER_HEAD_COVER_%2b_DECOMPRESSION_CABLE/XL500R-82-JPN-A/2Y14435ZE14435Z01C

This says the bolts are 140 long,they are 6mm dia, Easily & commonly stripped,unfortunately more often than not it's the crankcase internal thread not the bolt that's stripped or a combo of both,they must be only torqued to the factory specs,but even then they seem to fail often on these engines & the RFVC models,including the threads in the head holding down the rest of the rocker box,unfortunately they are very critical as the rocker box needs to be clamped securely as there is huge pressure as the camshaft turns acting on the rockers in turn acting on the valves,Hope you just have the wrong length bolts!

[adam.m]

Thanks mate 

The bolts are 140 long and 6mm alright. But they do look a bit worn. Maybe some new ones might be worth a try.
Im wondering if there is some kind of liquid metal could be poured in to fix the thread without pulling it apart. Actually, im thinking something was probably tipped in there as a dodgy fix in the first place.

[adam.m]

Or ... what If I cut a new thread into the head and used a bigger dia bolt. Would it matter that it didnt go right through the head into the cylinder ?

[crs-and-rms]

you will have to helicoil them

[09.0]

The thread will pulled, mainly due to not being undone before the main 8 mm bolts/ nuts. It puts too much pressure on them and pulls the alloy thread. Helicoil is the answer. Maybe you can do it from underneath? Take clutch cover off?

[adam.m]

Thanks guys ... off to the soggy Goaldcoast for a few days, will get back onto fixing the bike when I return.

[flower pot racing]

I've got those bolts in titanium and the rest of the engine bolts in Ti for that matter, if you want to treat your bike....

(or of course just buy standard new ones from Honda)

[TM BILL]

Dont piss around with helicoils especially if the hole is a bit worn . Get time serts fitted (Davey Crockett on here Joan to his mates ) can do those for you  or buy your own kit from Wurth and do it yourself.

[crs-and-rms]

tm bil live heard of time serts but havent seen them do you have a pic , are they a larger diameter ?

[TM BILL]

This demonstrates how good they are  Joan put me onto them a few years ago and i wouldn't use anything else now 

http://www.youtube.com/watch?v=z5Pz66PDezE

[chrisdespo]

I use the timeserts at work along with Helicoils the Timeserts are better but i have found a couple of jobs i couldnt get them in and had to use a helicoil, i would say as i tell my apprentices dont try and short cut do what is required to complete the job corectly.. it will be quicker in the long run remove the engine head and barrel and fit insert to repair the threads new rings a gasket set check the valves and it will run for years also check cam chain and guides. then the engine will be good and the bike not just bodged up as happens and later some other person has to deal with the problems caused and makes the bike worth more for you anyhow.

[brucey]

Heli coil's certainly have there place cause thats what hold most defence items together.

Elevating gearboxes for the Hamel field gun etc in fact every aluminium casting or billet machined item is fitted with a Heli coil

Dont forget that the wedging action of the coils is what bites in under severe load.

But this is designed for in the amount of material left for in the boss / spigot. and the material used 6061 7075 etc

Time serts first came on the scene cause it was the only way for a mechanic to replace the stripped out mag castings of the beetle crankcase Porsche too and Merc (Wurth get it) and do it properly please also note that the mag castings also failed and pulled with the time serts fitted
No wedging action for the heat cycles.

Yes i am a fitter and turner and have a mill and drill etc to clock the face centre and drill and tap very accurately where Heli coils fall down is the old wandering drill / off centre , cut with a blunt tap thats rolled around on the bottom of the draw and no lube.

Oh and another thing they come in lengths so 1.5 x  = 9mm long in the minimum for a 6mm threaded hole any more and its for looks not form

Good luck with it

Bruce 

[eric318]

I find that Helicoils go well on these motors. Never had problems. This looks like an easy job Assuming you have the cylinder on the bench.
Never used Timeserts, cant comment.

Alternatives:
- tap the holes for 7mm bolts (there is not much metal on the timing chain well side...)
- get another s/hand cylinder jug (lots of them everywhere on eBay)
- I wonder if any body has ever tried to use JBWeld on these sorts of situations, ... and dared to report

Note that, contrary to what the two pictures together could suggest, these two bolts do not go down to the crankcase, they only hold rocker cover + cylinderhead + cylinder.