chrisjw

Interesting & informative thread. I've never really gone into the plus & minuses of different fuels, but have learned something now, after having a google about. I've always used Byron Gen2 20%, which, hopefully is sufficient for my engine.

Is the clutch engaging with the spur gear?............Are the brakes binding?

I've now collected this from the seller......Thanks.......

They're about the most common Ofna Force engine..................

& after much googling & measuring, I Have just found a site in Germany that actually lists the dimensions of all the Force button heads & shims......& you are correct.....The used engine I bought as a .21, turns out to be a .25, although they both have 3.5 engraved on the side of the blocks....So, problem solved & spares ordered......A happy ending....

Well, that's handy........Modelsport replied to my e-mail & can't tell me the diameter of the button head..............

I have 2 identical Ofna Force .21 (3.5) engines.....I want to replace the button heads on them as one appears to loose a fit & the other has stripped threads where the glow plug screws in. However, on removing them & measuring both the bore size of the engines & diameters of the button head part that sits in the piston chamber, they appear different. One engine has a bore size of 17mm as does the button head & the other of 18mm. I tried fitting the larger button head into the other engine & obviously it won't fit. The larger bore engine (18mm) was bought used, so would you say that it may have been bored out slightly or had a different sleeve fitted or could it in fact actually be a .25 engine, as it has a .25 heatsink fitted that came with it? Unfortunately, the sizes aren't quoted on the site. Obviously I want to make sure I buy the correct heads & Modelsport have Force ones in stock. I've actually e-mailed them & asked for the dimensions of the .21, but any help or advice would be appreciated. Thanks

It's a great car & I'd never get rid of it..............Over the years, I've managed to source practically every spare part to the car, so I can practically build a 2nd one. I have also found a place in Berkshire, that can supply shells to fit, but they haven't got one that's really caught my eye.

I knew I shouldn't have commented on this thread..........Guess who's just joined the "Busted pullstart" club..........

It's this.........................It was originally made by Sinyih, which I believe was then taken over by Carson... I've had it 18 years from new & it still runs like a dream... Still got the original box too......

Are you sure fuel is getting into the engine?..........I had a similar problem & found that the carb needle hole wasn't lined up with the fuel inlet hole.......Undo the nut on the HSN & take it off. Put a mark on the nut, where the needle hole lines up with it. Screw it back on, ensuring that the mark you've made lines up with the fuel line......It wouldn't hurt to soak it all in a bit of fuel while it's off, in case there are any fragments blocking the holes.........

45 minutes!!!!!!!................mine was in the bin 40 minutes before that...............lol

The shaft is part of the crankshaft, not the pull start, so you just get the pull start.............

Yes...........I attempted that little feat once, but soon opted for your suggestion above.....I chucked it........lol

Sounds like that spring has either slipped out of it's position, or has snapped...........

It's probably just the one way bearing.......Undo the 4 screws holding the pull start, pull off the bearing & re-new it......I could be wrong though, so I'll let someone else advise you

Thanks for that....Sadly, it won't fit my car............Mine is a 330mm wheelbase & 300mm wide...........

Hi..... Can you tell me the dimensions (centre front wheel to centre rear wheel, length & width of the 1/8th scale shell please......I presume it's the unpainted one......Thanks.

Yeah....That's basically what I wanted to know, with regards to the stripped threads. Time to have a practice with the drill & tap I think. I wasn't sure, from first inspection, whether the o-ring could be replaced on the HSN needle, but from what you say, it can be, so I'll see if I can source some. Thanks for your help.

So, took my nitro for it's first outing of the year yesterday, but have encountered a problem.......It took a while to fire it up, but eventually managed it.......Kept it on the stand for a couple of minutes, giving it a rev up & then it died & I couldn't get it started again......Checked fuel was getting to the engine & that the glow plug was heating up....all fine. What I did discover, was that the threads on two of the screw holes that hold the heatsink down were stripped. I noticed it, because as I pulled on the pull start, a few small bursts of fuel escaped from the side of the engine where the heatsink sits. Another thing I noticed when revving it, was that the HSN screw was spinning, in other words loose, although it doesn't seem that loose when adjusting it with the engine not running. I have a spare engine (both Ofna Force .21), so I swapped the engines over & also the HSN needle assembly, but it appears it's happening on both.....Maybe it's something I haven't noticed before, but it doesn't seem right as this must affect the tuning. There is a small o-ring/seal positioned around the needle, which I assume prevents any movement & this may possibly be worn on both carbs & could be replaced if possible, although it would be weird for both to be that way, but the engines aren't new. (Great engines by the way.....They've never let me down) Anyway, I've ordered a new HSN needle assembly from Germany, which has been dispatched & should be here next week. With regards to the heatsink problem, the only way over it, as far as I can see, is to drill & tap the two stripped holes to a larger size (at present, they are M3, so I thought maybe drill to a M3.5), although I don't want to go causing more problems. Can anyone give me any help or guidance to get over the problem?....Thanks.

Everything on & adjusted.................Ready for it's first outing of the year...........................

ready to rock 'n roll......................

Wheels on................Ride height & camber done.................

Engine, clutch assembly & exhaust done....Just the wheels to put on & adjust suspension & camber.......

Servos, electrics, receiver, battery box & fuel tank in................