engine problems

[fergus]

Hi all,

I have recently replaced the sc32hr engine in my shuttle with a Webra 35 competition. I have the main needle screwed out 2 turns and have not adjusted the idle setting. the plug is working fine. fuel has 5% nitro (Morgan Fuels). Throttle servo operates from stop to stop. The problem- The engine is just refusing to run. I opened the throttle further by setting the trim tab to full and stick at bottom the engine ran with very little smoke and stopped as soon as the throttle setting was reduced. I don't want to try again in case the screws are way off and I cause damage to the engine. Has anyone experience with this engine or no what neddle settings to start with. I am a novice when it comes to model engines and I would be grateful for any advice.

regards,

Fergus

[Stuart]

Fergus,

have you looked inside the piston chamber for any scoring or marks, what plug are you using.

I'll check the net for a manual and have a read, I don't use Webra's also what pipe have you got on it.

[fergus]

engine problems

Thanks stuart,

The engine is brand new. I have not opened it but looking through the carb mouth and exhast port shows no sign of scoring. I am using an os no.8 plug and have tried replacing it. The muffler is the Stock Hirobo type supplied with the kit. I screwed in the idle and counted the turns- 2 and 3/4 turns! I removed the carb and tried the method described in ' Radio Controlled Helicopters' by Nick Papilon i.e connected 4 inches of clean fuel tubing. Set throttle opening to 1/6". Main neddle at 4 turns. Blow through fuel tube while adjusting the idle until air just flows. Ended up at close to the same position that I started with. No Joy!

Thanks again for the help.

Fergus

[Raptorite]

Hi Fergus,

I run a webra 50 GTH in a raptor 50, although I got the heli complete with pre setup and run engine second hand a while ago, I find that for some reason it always takes a long time to start.

By the sounds of it, the low needle is set too lean, if it wont run at anything below fast tickover and there is no smoke. One other thing is that webra's are a bit of an art to tune, as if you make a change to the low needle, you need to make the equal and opposite change to the top end needle, so for example, as in your case, you need to richen the bottom needle, so you must also lean out the top needle a few clicks to compensate.

I have in the past setup one of these engines for someone at the field, the model was a caliber 30 with the standard kyosho muffler.

Although it can be made to run reasonably well with the standard muffler, it does tend to strangle the engine a little, so it would be better to run either a zimmerman muffler or a tuned pipe of some sort with a larger volume. If you would like to stick with mufflers, then I would suggest that at some stage in the future you consider a 50 size muffler for it, the 30 ones are fine, but they have been designed primarily for .32 size engines which need a lower volume and more back preasure from the muffler than the larger .35 upwards.

I hope this helps, if you need any more help be sure to post here

Cheers,

Pete.