Motul 800 has a high burning point. When the oil is coming out of your exhaust it did not burn, I think the engine is running not hot enough for Motul 800 you might try out Motul 710 which birns up easier due to the lower flame point.
50:1 is very good works with all type of bikes you might go a bit less of oil for trials riding 75ml for 5l gasoline is my mix, (which is around 66.67:1). I am using 50:1 for my 89 KTM 500 cc 2 stroke enduro/MX bike works flawless.
I use Ipone or Putoline half synthetic with a low burning temperature as oil.
Gasoline is Aral Ultimate 102ROZ without ethanol or Aspen fuel.
My tip: You might stay away of any fuel with ethanol very bad stuff depending your climate the storage of a fuel mix with ethanol can be very short.
The later 199b engine with 340cc is much slower in any reaction compared.to 199a model in standard set up. The 326cc feels snappy against the 340 in my opinion.
I had mounted the lighter flywheel of the 250cc to the 340cc and that was for me a bit too much power you might try yourself.
Improvements I liked:
- carn swap fo 28mm Dell'Orto,
- rear silencer with less low reduction of the exhaust vapors.
- clutch improvements,
- no changes to the ignition, I can't see the super improvement beside less maintaince.
What we / I did back im the days with earlier Sherpa models we took a a garden hose cut off around 20cm then cut that piece up lenghtwise and mounted it with a hose clamp to the frame. That worked very well.
Check your slide, sadly AMAL uses the same material for the carb body and the slide which results and wear so the slide starts rattling around in the carb and if the slide rattles the needle will do it too. In the end or very soon you have a worn slide and needle and needle jet.
There are two fixes to that problem:
- a chromed slide for the AMAL or
- a different carb.
As non of the mentioned fixes are cheap I' am using a Dell'Orto PHBH CS in my 242 with great performance increase.
Finally I can now adjust the carb and it really has an effect to the engine, also the fuel consumption is lowered.
The bikes are very unique and so is the engine. The cam shaft is mounted down in the engine base and the valves are moved by rods. This is a very simple construction, but too very crucial to oil supply.
The first bikes had problems with the valve engaging levers not getting enough oil, the engines needed a certain time to build up oil pressure and to apply enough oil to the head.
I had this problem back then and needed new valve engaging levers which took Italjet half a year to deliver them back in 1983.I don't think there are any spare parts for this 4t engine available. Even donor bikes and engines are a problem.
The motor is not very suitable for trialsriding anyway, a 2strocke Italjet works much better, not being said that this is the best twinsbock trialsbike.
The engine sounds as it don't want to accelerate right and when it finally archieved some rev and you close throttle the motor want's to run away but doesn't have the power ... so finally decides to slow down.
- Timing of the ignition?
- How does the plug color picture look like?
I don't like to hassle around with heated parts and get burned by them, I recently got burned a lot while trying to replace roller bearings to a swing arm...
So now using ice spray to cool down the bearings and gentle heat with an hot air gun. This combination works very well:
- first heat up the parts where the bearings belong,
- then a spray to the bearings to cool them down,
- and finally let them drop in et celá.
I have been using Elf htx 740 for over 10 yrs now and it is with out a doubt the best oil I have used. Started using it in my Gasgas originally as its the only oil that stops clutch drag and allows me to find neutral easily. Some where years ago someone told me it was developed for motoGP bikes as a low friction oil to increase HP, not sure if that's true but who knows. I also use it in Bullys along with fibre clutch plates and once again, neutral is easy to find, no clutch drag or slip when starting and using the bike. I dont use it in the bully gearbox because it is really thin and if you drop the bike it pours out through the vent hole whereas conventional gearbox oil doesn't. GRO also make a really light oil that is really good also.Hope this helps cheers Greg
Yep I can confirm that to every drop of HTX oil. This stuff - albeit expensive - works fantastic in every twinshock bike I have used in different makes build from 1979 to 1984.
Sorry but as the compression apparently hasn't come back, at least you haven't told so.
The chance the engine isn't toast is not high instead the opposite. We might see or read about it ... Surly I wish you luck and will press thumps (if that can help).
Looking forward to pic's in the next couple of days.
I think the engine has suffered some damage it would be super interesting to know what.
I believe you have blown the rings and with them everything else touched by them. The bike got too hot to little oil which caused much wear hot blow by and you will need a new top job now.
My own direct experience of Bing carbs, were mostly down to rapidly wearing Slides and sticking float valves. Not only on Bultaco's but on Maico MX'ers as well. My respect for Mikuni carbs is borne out of never having go near them through several models of YZ125's and 250's.
My reason for favouring the Electronic Ignition system is based on the positive feedback I have encountered from a number of people I know who have fitted it to their own Sherpa's.
The Bing carburettor has a piston made out a softer material as the carb body to prevent wear to the cylinder. The piston therefore has to be replaced regularly. That is a good idea much better then other carburettor's of that era where piston and carb body where made out of the same material.
The PHBH Dell'Orto has too a softer piston then carb body.
The Mikuni VM at least also.
Anyway in my experience the Bing works asthonishing well when set up right and maintained.
The Dell'Orto is a bit complicated to adjust because of it's bazillion possibilities for adjusting if you have already 5 different slides to choose it's a challenge.
Bing's offer not so many possibilities but need spot on adjusting too.
Mikuni's or OKO carbs you can screw on and they work it doesn't matter how the carb is adjusted the engine starts and runs mostly OK. The main adjustment for OKO and Mikuni is which diameter you use. You can slightly improve the engine by fine asjusting in the carb. I have a 125cc rebuild to 200cc Yamaha and the original carb worked on the 125, is btw. with same diameter and slightly different jets also standard to the 175 and do the job even on the 200cc motor. So very forgiving carb model which pleases you fast.
The gas will not burn slower or even faster if you have more octan it will just ignites later.., with higher octane fuel you will have less chance of detonations'.
As more compress ratio the engine has as higher has to be the octane number.
If you use 100 octane but you could too use 95 octane nothing will happen the bike will run as usual. As a benefit you will never have any detonations. As more you cone near by the recommended octane rate as a minimum as more is the chance getting detonations under load.
gasoline with lower octane will have the tendency to be ignored prior to the spark plug, will cause heavy detonation and can damage the engine quite easy.
Mostly race gas or gas with high octane is of very good quality and has less indegrents that are just mixed to the regular pump gas by law or economic benefit as bio alcohol certain stabilizer and so one, thus race gas is often a bit better in power output.
In my personal experience I like Aspen gas very much invented for forest machinery and based on Alcylate instead on oil.
It burns without soot and without smell can be stored for years comes with 95, 98 or 101 octane but it is expensive.
For a clean exhaust and engine, your health and the environment a real good fuel.
Nice job and yes the aluminium parts should be as bright blue as shown in the picture. Just the snails they have not been coloured instead left natural in aluminium grey.
The parts on my bike are too purple by sun radiation...
Fuel/oil ratio
in Sherco
Posted
Motul 800 has a high burning point. When the oil is coming out of your exhaust it did not burn, I think the engine is running not hot enough for Motul 800 you might try out Motul 710 which birns up easier due to the lower flame point.