Hi all I'm looking for some advise on what I believe to be a k&b sportster not sure what size. I've had it running but it won't run for much longer than 10ons before cutting and I cant get it started till the next day. I'm running it on 5% nitro fuel. Not sure what I'm doing wrong as I'm new to this. Any help would be much appreciated.

The site won't let me post any pics until I have atleast 10 posts. Not very helpful.

Glow Plugs, if your engine is an older K&B engine you may need a plug with an Idle Bar!!! remove the muffler and look in the exhaust port, if you see 4 or 5 little square ports in the cylinder Liner you need an Idle Bar plug, if the Liner has a wide port you need a Mid Range standard plug like an OS 8.

I don't know much about tuning K&B carbs, but if it has an old Air Bleed carb you need to screw the Idle Needle "in" to Richen the Idle, and turn the screw out to lean the idle.
they are good engines. check the glow plug after it stalls, if it's really dry it may be too lean.

also, if it's 65 and you have a 9 inch prop on it that could be your problem, a longer prop will give more "flywheel affect", so try putting a 12x5, 12x6, 11x8 on it.

in my link you can find K&B manuals. maybe you can find your engine.
http://www.mecoa.com/kb/aero/aircraft.htm

Jim

https://imgbb.com/

Put your photos in that site, and just link them into your post. Always another way to skin a cat. Click the link below, you should see laces out!


https://ibb.co/Jqk9qhg

If the site doesn't permit you to enter links, send a PM to me, and I'll post it for you.

Sportster engines need big props. But a small prop won’t cause it to flame out and quit after a few seconds. That’s a fuel system problem most likely, or a bad glow plug. Use plenty of oil in your fuel in a Sportster - specially if there is a lot of radial play in the crankshaft bushing.

My recommended props for Sportsters; 10x6 for .20/.28, 12x6 for .45, and 13x6 for .65. I use 23% castor oil in my fuel for bushed crankshaft engines. This gives me the best results albeit with a bit of oil spray from the bushing (not a bad thing other than being a little tedious to clean up).