88 XC430 de-comp mod

I finally have the parts for this mod. I would like some advice from those who have converted an LC head before, Dukkman etc, I am planning to install it on th R/H side on the dome part of the head (on the slant) back towards the coolant spiggot (so I can still get at the plug OK) I am going to use a suitable length of T6 bar 5/8" dia and bore through slightly smaller than the dia of the de-comp valve head (in case of failure) then counter bore and tap to suit the Husky chainsaw valve. The advice I am after is how did anyone do the combustion chamber end ? My thinking is turn down said end to about 1/2" then bore/drill the combustion chamber to that size whilst boring a 5/8" hole on the water jacket side & get it TIG welded on both side's. Then clean up & polish the combustion chamber side back to the correct profile with a dremel.
Does sound OK or is there a better way of doing the combustion chamber end?? bearing in mind I only have my lathe & a pillar drill. Otherwise due to a back problem i may have to sell cos it is difficult to get the required kicking speed.
Sorry for the wordy post but I think words are easier to understand than my version of a workshop drawing.

Thanks for pic troublemaker. How was the combustion chamber end of the boss, inside the water jacket fitted?
Looks like a great mod, have you any pics of it in progress?
Thanks for the reply.

I didn't do it,I have a guy that does them for me.It appears that he welded up some of the water jacket then drilled it.

Thats how it looked, I am trying to avoid getting to complicated hence putting it on the angle & welding top & bottom? Just wanted to bounce ideas off you guys with helluva lot more husky experience & know how

Why do the mod? I was taught if your timing is set correctly it will start fairly easy. No big bore is easy I get it, but if I can't start it I feel like I shouldn't ride it so I'm not hurt lol. My 430 is a bear to kick sometimes but never takes more than three good attempts.

Easy for you to say, wait until you are numerous injuries and ailments later and in to your late 40's or older, especially if you don't have time to work out!

My first one was as you have said Husqyman but I threaded it into the combustion chamber as I had drilled through the water jacket and was worried about corrosion .
Starting from the inside I tapped the combustion chamber then had a flat seat on the top [ outside ] of the chamber wall then had a bigger hole in the outside wall.
Made up a thingy with the correct thread on the inside [ to suit the deco ] and a thread on the outside and a flat seat to match the one on the outside of the chamber then screwed it in hard , then got it welded inside and out. [ You can see the welds if you look hard ]
Worked well BUT I made the inside hole the same size all the way through.
If the deco valve was to fall/break off then it would fall into the cylinder. Dumbo



Then I saw the setup that Troublemaker has and realized that it was a better way so I copied that.
It is possible to drill through the web at that point and not have to weld the water jacket but you have to drill 2 small holes one on top of the other [ end up with an oval shape to get enough air movement ] to get them to fit and weld a boss on to get enough room/length for the deco to fit.
I drilled a 3/16 hole into the head and through the boss then stuck the drill in it and sent it away for welding. This kept the boss where I wanted it.
This way stops any problem with the valve falling off and is a neater solution.
Thank you whoever invented it.

Ignore the stays on the head as they were an experiment that hid the real problem until it got worse.
If your 400 vibrates then fix the rear mount holes in the cases and frame , this makes the problem go away .
And now a simpler way of explaining it.


To Outdoorsman
Here's one reason to fit one and if you have an earlier clutch cover without the extra bolt hole then the deco stops cracks near the kickstart as well.

Thanks dukkman
Thats what I was looking for. The side mount one is good, But I think I am going for the version similar to your original version, the de-comp valve I have is a Husqvarna chainsaw one with a push on/pop closed not quite as high as your one, I thought some sort of weld through sealer to stop the coolant ingress/corrosion problem (will post some in progress pics soon).
outdoorsman
I agree in principal, my 430 starts usually 4/5 kicks when cold BUT an L1 disc/S1 nerve route problem means I cant kick it like it needs!, riding it is not a problem. Adam I agree with you entirely @ 54yrs young I need all the help I can get
Thanks for taking the time to reply
Kev W

The only help I need starting my 430...is a step stool to stand on! 5'7" tall here.

The only tool I need is my brother Jim A step stool would probably work too but I would really look stupid with it bungied to the fender.

You sayin I look stupid?

Milk crate ?

Milk crate, step stool, rock, stump, someone elses footpeg, truck bumper, trailer fender, a ditch, done em all.

Well let's say the picture in my mind of myself would look stupid. You however are probably smart enough to hide a folding stool.
Besides your next post redeemed you.
I have been known to push a long ways to find a hill, even if I have to push it up first. That way I can use my best ASSet to start it.

You are lucky,there are no hills down here in hot ass florida.

Not many hills on the Romney marsh either.

I have finally done it , here are some pics. I used T6 bar 5/8" (15.8mm). The head was drilled (pilot holes) 5mm & then 10MM then 13.5mm right through, then 15mm through the water jacket only. Then onto the lathe, I centre drilled the bar 5mm right through (the head of the decomp valve is 6mm so if it falls apart it will not drop into the cylinder), then turned down the 1st part to 13.5mm and the 2nd part to 15mm, counter bored the thick end (8.5mm) then tapped it M10x1.0 for the decomp valve. all done in about 2 hrs. just got to take to the local welders to be tig'd up on Monday

Some others Thank you for all you input it was a great help, because the 1st step is always the hardest. All I need is for the head gasket to arrive from Andy @ HVA, Oh and the welding.