I have a hyper 7 .21 motor. Pull start broke, im using bump box. I noticed it is leaking fuel out from the motor somewhere. Im runnning byron %33 nitro and %16 lubricate. Could be coming from the broken pull start? Do you know where you can get a blank back plate?

Welcome to the forum. First 16% oil content is TOO high. I an most do not recommend more then 12% as to much oil can do as much harm as good. Is it coming from the front of the engine or the rear? I would think you can get a plain backing plate for it buy you will either have to cut the crank or get another one unless someone makes a plain backing plate for a pull start engine.

i know when you take off the pull start there is an open spot. try finding a diagram of it on ofna.com and see whats behind it

There is definitely a bump box backplate for a Hyper 21. They are about $8 and readily available. About the fuel, check the fuel lines at the carb and the fuel tank and see if that is where fuel is spilling.

It looks like it is coming out where the exhaust meets the motor. Soon to find out that gasket is bad. But if the gasket was good it would seem like there was a lot of nitro going into the pipe, which cant be good? And where can you get the back plate, i have looked but cant find the one for the hyper .21

Thats because its very rich. Have you finished the break in procedure? If so lean it out more as it sounds like you way off a decent tune. As for the seal, have you moved the engine or pipe? perhaps its not sitting on the gasket properly?

Small fuel leaks are actually normal. If it's leaking pretty bad at the exhaust port, then you may need a new gasket, or the pipe isn't seated against the block very well. You may want to look in between the head and block, make sure it's not coming from there and running down on the back of the engine. If so then re tighten your head bolts. If you are using a bump box, then by all means order a non-pull start back plate, and completely remove the pull start assembly. This will make your engine happier as far as tuning, power, and temperature. Here's a link to a non pull start back plate; [link=http://www.nitrohouse.com/catalog/product_info.php?cPath=34_134_283&products_id=1315 2]hyper back plate[/link]

Thanks for the link to the backing plate. It seems to be tuned good running at 200 degrees, i think its because my fuel is %33 nitro and the motor cant handle it. I'll lean it out and see what happens.

Also what shocks do you all run? I have a hyper 7 with all the hoboa hop ups on it, Its way too heavy.

Anybody?

I'm running the 14MM shocks. The lighter the buggy, the smaller the shocks you'll need, or that's what works for me. You can lighten it up some by using graphite servo tray, and front support. They also have engine mounts that are lighter, and give a lower COG, universals and CVD's are lighter than dog bones too. If you add the weight of the front and rear dog bones, and the axles that go with them, they will be heavier than the CV or universal counter parts. Using thinner rear shock towers is a big plus, because it's less susceptible to damage so you don't need the extra thickness. If you're using 16MM shocks, then that adds a little weight too, so if you can tweak the 14MM shocks to satisfy you, then by all means do so. The Hyper PBS used to use aluminum center dog bones, and if they are available still, try a set of these to help reduce more weight. The Hyper 8/8.5 uses lightened center diff gears, and thay are pretty cheap on E-bay. Not the 8-gear spider diff, the standard diff. The spider diffs add a ton of weight, and the standard diffs have worked for me for years, so I have never seen a need for a stronger diff, even in a truggy. I hope this helps.

Its not the 33% nitro content, more likely the 16% lube content the motor cant handle.