I switch my feul from 10% to 15% on the advice of my lhs. Last night i ran the last of my 10% and all went well. when i filled the tank with the 15% all I could do (if I could get the plane of the ground) was practice dead stick landings. I tried to adjust theneedle valve, on the bench it would run fine. it ran at idle or full throtle even pointed strait up. If I put it on the ground it may stall after I taxi to the runway or if I reduce the trottle while flying. It is getting colder here about 45 degrees but the first tank (10%) ran well and I was told that the 15% would run better in colder weather. havent seen anyone at the field for a few weeks now so I could use some advise. Thank you

RJV, you're either too lean or have bad fuel[:@]. Try some 10% again and if that works, take the 15% back to the LHS.

Yeah. He might have recommended 15% because he had a couple of "old" gallons sitting around.

I'd look at the "too lean" suggestion first. Because moving to higher nitro fuel also requires a (slightly) richer mixture setting.
Dennis-

I second Dennis's reply, in fact he said what I was thinking before I read his post! Both on the "hey kid, you just GOTTA use 15%", and the slightly leaner setting. Also you should run an engine on the same % of nitro for the beggining to the end of it's life cycle, except for a REALLLLLLY old one, sometimes it helps to go to a higher % at the end.

Jetts

Since you are out of the 10%, see if you can get some from someone else. It does sound like bad fuel, but the LHS will probably disagree. You may also want to try a new glow plug. It sounds similar to one one of my problems and the glow plug fixed it.

Shake the container and hold it up to the light. If there is precip floating in it, it is bad.

Clean out your carb and inlet. May have gotten a spec of dirt in it causing the problem.

Check it with the other fuel and if the problem is still there, change the plug. You may have run it too lean and ruined the plug. I would change it first and try the 15% again.

RJV,
Just curious, why did your LHS say you should switch to 15%? Is this a 2 stroke or 4? If the engine is a 2 stroke and was running fine on 10% there's really no reason to change, 15% is just gonna cost you more $$. On the other hand, 4 strokes usually do run better on 15%.

First, thanks everyone for the repleys, I'll be working on this more over the weekend. I did look tonight at the feul and it looks o'k. I also removed the glow plug (it is the original) and pluged it in the battery and the glow was noticably smaller than a new one, a #8 but I do not know if the old one is a #8 but that is what towwer hobbies recomended when i ordered the plane

Stick jammer, I have a o.s. .40 LA. I've run 1.25 quarts through it so far of 10%. The person at the store told me it would start better in the soon to be cold winter weather. I asumed it would also run better and was in a bit of a hurry so did not ask any more questions. It also seemed most of the club members run 15%.

Stick with 10% on that engine. 15% will most likely ruin a bushed engine in short order.

Not being on to argue (sure yeah right) but 15% is not going to ruin a bushed engine in any time soon. I know people who've run nothing but 15% in bushed engine(s) for years with no damage, including me with an LA .40 for some time now. Flyboy's right on. new plug, check the carb/fuel line.

Jetts

I don't see that engine needing a nitro boost. A better solution to running your engine in colder weather is to check the head temp and see how hot (or cold) it's running. A good head temp at the glow plug is around 300 - 350* F. If it is noticeably cooler than this, blocking some of the head fins would help to raise the temp. A cold running engine will not burn fuel efficiently and will run as though it is way too rich.

Jesse

A bushed 2-stroke is not built to be pushed to the limit. If you want more performance then go to a ball bearing engine. But as always, to each his own. Just my $.2

Yes yes! Indeed,- 15% in not "pushing to the limit" with a bushed .40. Unless things have changed conciderably, 15% is pretty much "standard fuel". 9X6 prop, 25% nitro, now that's pushing it.

Jetts

OS does state that the LA series can run on fuel with 5% ~ 15% nitromethane. Following this information that OS has provided, it would seem 15% is the limit. Don't get me wrong, I'm not knocking anyone that chooses to use 15% in a bushed engine, but that engine should run just fine on 10%. More nitro = more heat. More heat = more friction. More friction on the bushings = more wear. OS doesn't care, they'll gladly sell you a new engine.

Actually, I'd say the 9 X 6 prop and 40% heli fuel would be pushing it!
Dennis-

Judges?

Yes, actually I buy 15%, and then ad a few oz. of castor. I run this mix in ALL my engines, 2 stroke, 4 stroke, bushed, and ball raced. Even ran my K&B Sportster .45 on this fuel for so many flights, I lost track. The key is not trying to get every last bit of RPM out of them by running the nearly to lean.
BTW that's 4 oz. of de-gummed castor, and 2 drops of Armor-All ( it was originally used as an industrial de-foaming agent) to a gallon of 15% nitro 18% oil 50% castor 50% synthetic fuel.
Never had a seizure, never wore one out, period.

Jetts

There you go. Most people don't add anything to their fuel. I think we have gotten a little side tracked from the original post. Which brings me back to the question of why RJV needs 15% for a bushed .40? 10% was working fine and he did not mention any performance issues. 10% is also easier on his wallet, so why change?

I think the higher the nito the more power. I ran 30% heli fuel in my Saito 100. It was $32/gal but it ran great! I read in a major RC magzine, that a tired old 2C running 10% will actually run better on 5%. I can't remember the explaination, but, the article made sense. Anyone else heard this?

i got my .42 tt engine going to day i just bought it because iam a begginer .i could not get it starthed for a little bit but i cept ajusting the engine than it would start that it would run good but it would stall. why would it stall all i did was bring it out side when i got it started but then i guess the tempiture was -10 .c does the cold air stall it?. or wat is happening

A new ABC engine and cold weather is not a good combination. The engine needs to heat up so the sleeve will expand (part of the technology of ABC). If you don't get this heat then the piston will wear the sleeve and damage will occur very quickly. You can put some aluminum foil over the fins to keep it from cooling too quickly. Running engines inside is not a good idea even for a little while. Get the engine warm by keeping it inside and let it come up to room temperature. Go outside and immediately start the engine. Make sure the igniter is fully charged.

EXCAP232

Stickjammer,
If you'll re-read his original post you'll see why he changed from 10 to 15%.
Dennis-

I already knew, because his LHS told him to but did not give him a reason.

Hollo gentlemen, thought I would give an update. First, my last post had a mistake. I've burned 1.25 gallons not Quarts of the 10% as stated.

I went out saterday. A lot of problems with the overall performance of the plane so I went through everything from adjusting the throughs to checing c/g ( I've had my strugles learning to land).

As far as the engine is conserned I spent a lot of time adjusting the mixture. had it runing better but it seemed slugish. Longer takeoffs and did not want to clime. that landing was a bit rough (variable and gusting winds), I broke my 11-5 prop. I installed my 10-6 and tried to lean out the mix. It sounded good but another long takeoff and after flying about 5 minutes I reduced the throtle and the engine stalled. On the up side I landed the plane dead stick with the wind and only one small bounce.

I look at these challanges as part of my education and am greatfull for your advise and coments.

Try reading the first post one more time. He said he was told that the 15% would help the engine run better in the colder weather.
Dennis-