my 3.5 wont start K&B

[Dave Miller]

my 3.5 wont start K&B

??? ive got a second hand 3.5 k&b outboard ive been trying to bench start for hours with no luch was hoping i could get some ideas from you all. Ive tried all of things i can think of. i cant even gey it to grunt.just turns over. Good hot glow plug (2 new ones have been tried) inlet and outlet for fuel is hooked up/ very strong compression. It doesnt seem to like to stay primed if the throttle is at idle nor will it draw fuel unless ive got the throttle at 1/3 or more open. AT that point fuel will flow and drip out of a hole in the bottom of carb(black) ive watched threads here and tried the suggestions Jerry had but no luck. could something be wrong internally. I took it apart for inspection but am pretty sure it is all together correctly (though not as sure as i was before) the crank has a "L" stamped on it. is this right for the outboard? Im really soory this is soo long but want to be detailed and am really depressed that i cant get a simple motor to run. Any and all help would be VERY appreciated. Oh and the fuel ive got is fresh 15% nitro w caster/syn blend is this ok to start it with?

 

[Grimracer]

Re:my 3.5 wont start K&B

Dave

To begin the fuel you have needs to go. I mean it might run on it but if it does run it will likely cause damage to your motor. 15% is OK but the synthetic has got to go.

You say the motor has good compression but it is having a hard time drawing fuel. Take some light oil (wd-40) and place it down the glow plug hole. Reinstall the plug and turn the motor over by hand. Just get the piston over top dead center and then rock it back the other way. Repeat this and see how many times you can compress the same air. If it it less then 6 or 8 times the piston and liner fit is gone and needs to be replaced.

Are the bearings OK. Take the PTO off the motor and try to blow through the unit. If you can pass any air through it needs bearings. Repeat this with the front housing.

If all else fails send the motor to me and i can check it out.

Grimracer

www.grimracer.com

 

[duc]

Re:my 3.5 wont start K&B

Sorry to interrupt in this topic but I'm very curious about one thing:

What is wrong about the synthetic oil? In Holland we all use synthetic (the blue oil from Graupner) mixed with caster. 14 % syn + 3% caster. ???

Don't get me wrong. I'm not saying you are wrong. Just curious......

 

[dave miller]

Re:my 3.5 wont start K&B

ok ill pick up some fuel without synthetic oil in it. what should i get? 25%? the compression is soo strong it is VERY hard to turn over by hand and im i pretty good size guy. id id the testr on the bearings and i am not able to blow any air through them. If i am not able to get it to run I might send it to ya what kind of charge would i be looking at not including any parts that it might need? The inside of the motor was very clean and there was no scoring in the sleeve/very smooth. The pistin gets very tight at the top of the sleeve even without the plug in. ive been told that is ok?right? I appreciate your help and ill keep trying.

dave

 

[Grimracer]

Re:my 3.5 wont start K&B

Dave

It sounds like the motor is OK. However i might be carfull about the fact that it is tight at the top with out the plug in it. Most of the time this is OK but i have seen K+B that have a crooked liner flange and can pinch the piston at TDC. This would take a bit of work to fix but it can be fixed.

I would not charge you anything to go over the motor. At least this time. The parts would cost you if it needed any but that is normal.

If all is OK then this would cost you shipping and that is about it.

O yea 25% is just fine

Duc.

As you might or might not know I run Byron fuel (sponsor)and it is a castor syn blend. I have had bad luck with pure syn fuels thats all. I have lost more then one motor using syn fuel and do not care to lose another. Maybe i have a bad ear.. Also after working in the hobby industry for 10 years and having to service motors for most of those, i have seen more then first hand the dammage it can do. It seams to me that bearings just do not last long enought using pure syn fuel. Pstons become color died and scored. Makes me cringe just thinking about it.

If you can make it work please share your methods.

Later dudes..

Byron fuel rocks

Grimracer

 

[TimD]

Re:my 3.5 wont start K&B

I thought i'd jump in on this castor/ synthetic argument.

I am a strong advocate of castor oil in the fuel as it is more tolerant of a lean run without killing the piston. it also seals the motor better giving you better compression, and it also draws more heat out of the motor than synthetic as it is less likely to burn.

Like grim, I also worked in the hobby industry for years and have had to replace a lot of pistons / liners that were killed prematurely. I would NEVER run fuel with less than 5% castor in it, and 20% total oil content.

 

[duc]

Re:my 3.5 wont start K&B

Ok Grim and dave, Much appreciated. I will open a new topic about this since I'm breaking in here...... :-X

 

[dave miller]

Re:my 3.5 wont start K&B

Well i got some sidwinder 30% and still no go. This is really bumming me out. ???

 

[ggillman]

Re:my 3.5 wont start K&B

Dave,

Lets run through a basic checklist here and see what we can find:

1) Fresh fuel

2) Fresh glowplug

3) Looking at the motor with the glowplug facing you, Is the starter turning the flywheel clockwise?

4) If you prime the carb (put just a little dab in it) will the engine run a second and then die?

Gene ;D

 

[dave miller]

Re:my 3.5 wont start K&B

The fuel is brand new today and the glow plugs are new as well (ive tried 2) I have not gotten so much as a sputter out of it. It is turning clock wise. I have the needle set a 4 turns open but have tried everything fron 2 1/2 open all the way to 5 turns open. If i leave out the glow plug and cover the carb while turning over it(fuel) will spray out the plug opening. I feel REALLY stupid about all this i cant believe i cant figure this out. im fairly mechanically inclined but just cant gey this bugger to work.I really appreciate all of you trying to help me. Its nice to know that the people in this hobbie like to help each other. I probable would have given up by now otherwise.

 

[Grimracer]

Re:my 3.5 wont start K&B

Dave

You can not be far off.. However i have seen K+B motors without ports milled, bearings that are bad from the factory and the like..

If you can not get that puppy fired send it to me to be checked out.. I will scope it out for free. Of cource if it is fast it might take some time to get back to you (Kidding)LOL

Grim

 

[GRand]

Re:my 3.5 wont start K&B

i wonder if the piston could be in backwards? i cant remember what the K&B 3.5 piston looks like (skirt wise) but i have fixed other peoples rc car engines that wouldnt run because the piston was in backwards either from a rebuild or from the factory.

 

[ggillman]

Re:my 3.5 wont start K&B

Dave,

I would send it to Grim, he is a sharp cookie and a honest dude to deal with, he will get ya goin.

Gene ;D

 

[dave miller]

Re:my 3.5 wont start K&B

Ok I think ill do just that. im sure that im just not doing something right ill try one more time and then ill send it out to Grim. I really appreciate it. let me know where to send it and ill get it to ya. Thanks again guys.

 

[dave miller]

Re:my 3.5 wont start K&B

my email is [email protected] if ya want to use it

 

[Grimracer]

Re:my 3.5 wont start K&B

Dave

you can find shipping info at www.grimracer.com

Send it asap, that way i can get it back to you so you can begin enjoying you new hobby..

Grimracer

 

[david miller]

Re:my 3.5 wont start K&B

hay I got it running Ive been trying to start it with a gear reduction starter that i got with the boat and it was not turning over the motor fast enough. I picked up a sullivan starter and bam it fired up almost instantly. It sounds like it will scream. im soo siked im gonna put it on the old hull and see how she goes. by the way it is an old Dumas hotshotIV any thoughts on how fast it might go? it was designed by jerry Dunlap i think? I believe it is pretty old. I just want to say im very appreciative of all your advice and offer to help.

Im sure ill have more things to ask in the future if you dont mind.

thanks again!

 

[eric ekern]

Re:my 3.5 wont start K&B

my first boat was a hotshot IV with a stock k&b 3.5. 30-35 mph is what i would expect. its a fun boat

 

[Grimracer]

Re:my 3.5 wont start K&B

Just goes to show you that even though we have been doing this hobby for some time, that there are things that can still catch us off gaurd" the starter was the problem"..

You know that i have run in to this before and the thought never came to mind. Was it a Kavan starter??

Man o man

Grimracer

P.S. Just in case, the offer is still good on the motor thing.

 

[david miller]

Re:my 3.5 wont start K&B

yes it is a kavan. pretty much useless I guess. it starts right up not. I cant waite to get it together and try it out. Im having trouble getting the throttle cable to work right but i think i just need to get it adjusted right. ill let ya know how it runs in the water as soon as i get it out. Again thanks man i really think it is great how you all help out in this hobbie. Do you know of any upstate NY race locations? I would love to go watch a race. I live near ithaca NY 45 miles north of syracuse.

thanks again,

Dave