re500

Woody Many thanks for taking the time to have a look for me. Extremely usefull info'. Following your first post i have simply modified the carb on the 4T so that the choke is now a air by pass. Not fresh air, but additional air from the air box. Very easily done invloving no irreversible changes. Now when you operate the choke lever the engine revs increase, max around 5mm lift until too lean to run. In my next trial i will try 'very hot' starts at 5mm and full lift and see what difference there is! Hope the weather doesn't turn cold...as theres no choke start now! Again, many thanks for the help. Cheers RE500

Howard Wallace You certainly wouldn't want to try to start mine by hand, unless you like hospital food! Do you access the decompressor thro' the 'triangle' cover? cheers RE500

Woody Many thanks for the explanation and info. Wouldn't be differcult to fit to the carb' especially ~1/8" tube, like the overfolw pipes. Any measurments you can find would be much apprieciated. Cheers RE500

Hi Anyone taken apart a hot start system on their 4 stroke Enduro/MX? How big is the jet(?) that allows air into the intake manifold? Can you see any pipework externally, if so what size is it? Does the engine run (fast) with the hot start in use or do you close it as soon as the engine fires? Any info would be usefull.. cheers

Howard Wallace Very interesting, this would explain why others seem to use little effort yet i need to jump on mine! Any idea what was done to fix the problem? As an experiment i fabricated a longer kickstart and used this at the last trial. Although it was MUCH easier to kickover (there is now some feel to the kick) the engine was still differcult to start when very hot. Seems others have suffered the same hot start problems as i have. Heard that some are fitting a 'hot start' device off the 4 stroke Yamaha Enduro/MX. Maybe this is what the 'new carb' being designed by the factory that Ishy mentioned of in a post will have? RE500

Howard Wallace Good tip re the radiator, i dropped my engine in the frame to check mine and still had to unbolt the rad, though i didn't need to remove it. None of the valves were out of spec. Jools There are service tips specific to the 4T on the Sherco website. These cover all the usual service requirements. Sucks for those that dont have web access and really should have been supplied with the bike. Worth having a look even if you don't have the bike as they have plenty of detailed photo's. RE500

Webmonkey Thanks for your experinces on starting the 4T. Interesting about the choke, will try that, although when cold its not really been a problem. I have also found that 2 stroke type kicks do nothing except waste energy. I have tried to use the same method as i use on my P65 bangers but there is very little 'feel' in the kickstart...i would much prefer a manual decompressor! I have fabricated a longer kickstart for my 4T and this seems to have helped, although i haven't tried it when 'trial hot', just pratting around on the drive hot. It seems easier to feel whats happening to the piston/stroke with the longer kickstart. See how it performs tommorrow... Cheers

Ishy thanks for the reply. If this is all they did to the engine, i'm very dissapointed with the quality of the original assembly. For the seat lapping to have this much impact on starting suggests they must have been very poorly done ( if at all) originally! Cheers

Ishy I would love to know what has been changed to the later 4T to make hot starting better. Mine can be a nightmare to start when hot Webmonkey Suprised to see you say starting 'Doesnt need a lot of effort either', mine requires massive ammounts of effort to kickover. Much more than any 2 or 4 stroke i've owned! Even considered fabricating a longer kickstart! It has to be said though when runnig it is an awesome machine expecially in the mud down south

Hi Anyone fitted a smaller pilot jet on their 320 4T ? Adjustment screw is ~ 1/2 turn out on mine, appears rich, riding and the appearance of the plug confirms this. Seems a smaller pilot jet would be worth trying. However standard VHST pilot jets are slightly different to those in the 4T VHST carb' , the standard jets have smaller cross holes! Cheers

Marlintec Yes, they have changed something, there is significantly more room in your picture Bike comes with a poster of last years 04 2 strokes. Only imformation on the 4T are the service tips on sherco.com.... and your posts! Dealer hasn't done one yet! RE500

Marlintec Yes, did have a half hearted go, just to have a look at the decompressor! See attached picture, cover is outside and under frame rail, it cant be lifted and across as the plug tunnel stops it(?) Cheers

Marlintec Again, thanks for the info'. Unfortunately the top valve cover sits outside and under the frame rail so is impossible(?) to remove without dropping engine. Just no clearance to lift the cover up and off. Cheers

Marlintec Many thanks for explanation regarding the decompressor, seems like a neat solution, assuming its reliable ! Has anyone checked the valve clearances on the 4T yet? Any tips for saving time..seems to me the engine needs to be dropped in the frame to remove the rocker cover! Must be a simpler way? Cheers

g4321 Sherco state in their service tips for the 4T.. Change oil after the first 5 hrs and then every 30 hrs thereafter!!! I think i'll play safe and change a little more regularly than that! cheers

Big John Its 100cc /700cc according to the service tips. Anybody know how the mysterious decompressor works as mentioned in the T&MX bike test? Cheers

Marlintec Just did a quick test of the carb' bowl temp. Thermocouple was tapped to the bowl, heatshield side. Ambient 21C Fan cuts in 25C 37C after ~12mins riding on the drive, ie no load. Stopped engine, heat soaks into carb ~8mins. Max 40C !! However don't think bike is as warm as in a trial, it was still posible to sit on the seat. Kicked it over and started 2nd kick. Anybody know what the max temp of the fuel should be? Cheers

Marlintec Yes i measured surface temp of HT Coil. Also measured silencer temp ~ 155C. Didn't measure the oil temp, didn't want to stick the thermocouple in the engine without knowing where its going and more importantly coming out! I can understand how the mudguard melted..mine gets too hot to sit on and as i said to Big John, even the frame rail gets too hot to touch! I have already spoken to a F1/Champ car exhaust fabrication company to see what we can replace the silencers heat shield with. I have emailed him with photos of the sheild/insulation. He had some excellent suggestions as to what to try, unfortunately he's off on holiday for the week! see pic of heatshield, unscrewed from silencer...seems a bit thin in insulation. Cheers

Big John Sadly the 'old fashioned way' doesn't work for me, no problem with the 500 and 350 Bullet Trials though, first kick everytime! Did you get yours really hot..like you can't touch the right hand frame rail hot? Inlet manifold is neat....mine looks like its alive and 'breathing' rather heavily..like the pilot! cheers

Big John No choke..seems yours is the same as Dixies'. When you clean the carb' perhaps you could post the jet sizes/float level! Seems mine is the only one that struggles to start when hot...weird. Does your carb get warm to touch? Mine seems to pick up heat from the silencer, not sure if this is the problem but would have thought ALL 4T's would exhibit the same failure to start if it was. Measured the temp of the coil while practising yesterday. Ambient 18C , Coil 53C after ~ 1 Hr riding, pretty much non stop. Cheers

Here you go...

Marlintec The needle valve has a bent thin gauge wire fixed to to the top that forms a loop. This hangs onto the float arm/lever. The float arm/lever doesnot have a notch for a T shapped needle valve to fit. Does this make any sense...if not i'll take a picture tonight. Cheers

Marlintec Does the PHBL float needle have a spring on top ? Carb doesn't seem to get warm at all, even when the motor is well toasty. Thanks for the suggestions though! Haven't popped the tank off to check the temp of the coil, i'll stick a thermocouple to it and see.

Marlintec My 4T exhibits some strange carburation, seeming weak, then rich for no apparent reason. Following your link, the google translation is not perfect but it would appear you have identified a problem with manufacturing of the float needle and housing. Am i reading this right? You solved it by fitting a float needle/seat from a PHBL type? Was it a straight swap?

Dabster measured my 4T float level and is 18.5, so appears same as 2 stroke, 4T Stock carb' setting...on mine! Slide 45 Pilot 32 Main128 mixture screw 1.5 turns out How does this compare to the 290?