Allen or hex head bolts?

[Dolomite_]

My engine is fully stripped and the cam tensioner hole has been repaired.

Quite a few of the original hex bolts are worse for wear so I've been looking to get at least the crankcase bolts replaced. Is there a best choice when choosing between allen or hex head bolts? There seem to be a lot more allen head replacements.

Can anyone recommend some companies that do sets of bolts? I've seen CMSK mentioned and they do a good range of allen head bolts, but if i can get them from somewhere where I dont have to pay £20+ on postage, that would be great

[McCabe-Thiele (Ted)]

Someone here will know a good supplier of bolts - My engine had SS  allen key headed bolts - the top ones hold water so I changed my upper ones only to normal Hex head it was a while ago I think I contacted someone called Tina - TSS fastners iirc.
I retained the Allen Key headed bolts on the lower casing to save a bit of dosh as I am well over budget.

Others here will confirm.

I just checked my top bolts came from Middletons I used Tina for some cam cover fasteners.

[taysidedragon]

Stigs Fasteners does bike sets for many models Inc 400f. Stainless Allen heads.
I got mine from him, good service and good prices.

a2stainless.co.uk

[Dolomite_]

Thanks! I'll check those out.

Is there a benefit to changing from hex to allen heads?

[TrickyMicky]

If you are in a position to be able to use good quality sockets and spanners, I would be tempted to stay with the hex headed bolts.  Where socket head type fixings became popular was in replacing the Phillips type screws on engine side casings, much of this was before we discovered the existence of JIS tools!!  On a purely personal note, I don't particularly like the appearance of of full socket head screws on these casings, I think it gives a look similar to a piece of Military equipment. I have used button headed socket screws on these cases, the head shape being not too far removed from the original. Just a personal opinikon, and no criticism intended.

[andy120t]

I put some shiny Allen bolts on my engine casings and I wish now I had used hex ones ... they look more original. I'll swop them at some point.

[Laverda Dave]

I've just purchased a complete set of stainless JIS screw set for my 400/4 from this company;
https://www.ebay.co.uk/itm/265837463287?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=6JNVwhUGQuS&sssrc=4429486&ssuid=5XpGce3OSuS&var=&widget_ver=artemis&media=COPY

[Johnny4428]

I had changed all the engine casing screws for allen head screws when I restored the K3, but didn’t like the look especially when I had gone to the trouble and expense of going through parts lists to try and put fittings as it was meant to be. All changed now for JIS screws.

[McCabe-Thiele (Ted)]

Agree with what has been said  a lot is personal choice - visually water pools in the Allen Key heads is not a good look. Even stainless will often show some rust staining.

[ka-ja]

it depends on grade of stainless, 316 grade does not show rust, but a lot of bolts etc on sale as stainless are made with 302 grade, and can show some rust signs.

[McCabe-Thiele (Ted)]

True but it can't stop the Algae growth. Lol

[Mikep328]

I removed all the aftermarket hex head fittings that were on my 400 when I bought it and replaced them with the OEM JIS screws.  I much prefer the original look now though I admit that back in the day with my various UJM motorcycles I removed all the OEM JIS screws and replaced them with hex/Allens.  Go figure...