bunch of Grubee GT5 questions

GoldenMotor.com
A

andy b.

New Member
Jul 14, 2010
55
0
0
PA, USA
I finally got my new kit installed and have a bunch of questions. This is my first one of these kits and I'm not as familiar with 2-stroke engines as I am with 4-stroke ones. I had a Yamaha Banshee many years ago, but it always ran good so I didn't have to mess with the carbs at all.

The small plunger on the carb next to the idle screw, is that a primer of some sort? From reading other threads, I am guessing that is what it is. Do you push on it several times like the priming bulbs on weed whackers, or do you push it down and hold it in for several seconds?

When starting the engine, once the engine starts, how long should you leave the choke lever up?

When I first started the engine yesterday, it would start and then run okay as I was going down the road but would die when I put the clutch in to let it idle. The engine was only running for maybe a minute when I did this. I did this two or three times, and now the engine doesn't want to keep running. As long as I am going downhill and pedaling to keep the speed up to maybe 8-10 MPH, the engine will run, but once I stop pedaling the engine slows down and then starts sputtering and stops. I have read mention of the engine "4-stroking". Is there a YouTube video posted that shows both a normal running engine as well as one 4-stroking so I know if that may be my problem? If it is, various posts seem to recommend that I should move the needle clip one notch higher. Is that correct?

Also, is there a "Ask all of your Grubee questions here" thread that I may have missed?

Thanks,

andy b.
 
Mind_Reader7

Mind_Reader7

New Member
May 1, 2010
392
1
0
Northam, Western Australia.
andy b. said:
I finally got my new kit installed and have a bunch of questions. This is my first one of these kits and I'm not as familiar with 2-stroke engines as I am with 4-stroke ones. I had a Yamaha Banshee many years ago, but it always ran good so I didn't have to mess with the carbs at all.

The small plunger on the carb next to the idle screw, is that a primer of some sort? From reading other threads, I am guessing that is what it is. Do you push on it several times like the priming bulbs on weed whackers, or do you push it down and hold it in for several seconds?
It lets more fuel into the fuel bowl. If you take the carb apart you'll see how it works. Holding it works fine. I press it 3-4 times.

When starting the engine, once the engine starts, how long should you leave the choke lever up?
I only use the choke when it's cold. You should be able to tell, once it kicks over a bit, and sputters, put it down again.

When I first started the engine yesterday, it would start and then run okay as I was going down the road but would die when I put the clutch in to let it idle. The engine was only running for maybe a minute when I did this. I did this two or three times, and now the engine doesn't want to keep running. As long as I am going downhill and pedaling to keep the speed up to maybe 8-10 MPH, the engine will run, but once I stop pedaling the engine slows down and then starts sputtering and stops. I have read mention of the engine "4-stroking". Is there a YouTube video posted that shows both a normal running engine as well as one 4-stroking so I know if that may be my problem? If it is, various posts seem to recommend that I should move the needle clip one notch higher. Is that correct?
There are several things you can do. Adjust the idle screw
Move the C clip on the carb
Tighten the throttle cable a tiny bit.

Also, is there a "Ask all of your Grubee questions here" thread that I may have missed?

Thanks,

andy b.
Click to expand...
There you go. It's 3.30 am, so my answers were a little short :)
 
A

andy b.

New Member
Jul 14, 2010
55
0
0
PA, USA
Okay, I've been reading here all day and playing around with this engine. I found the specs to check the CDI unit and magneto resistance values, and they look good. If I put a sparkplug into the plug cap and hold it against the engine head while pedaling down the street I get a nice blue spark, so the ignition system seems to be working. I also pulled the magneto side cover off and all looks well in there.

Fuel flows in a nice stream out of the shutoff on the bottom of the tank, and if I pull the drain plug on the carb fuel bowl I get a steady stream of fuel out. If I run down the street a few times and let the clutch out to try and start the engine, and then pull the sparkplug, the plug is wet with fuel, so it appears fuel is making it to the engine. I have the clip for the needle on the stock middle position.

The engine seems to have excellent compression and I don't see any leaks from the head or exhaust or carb anywhere. I am using 89 octane gas and about a 16:1 mixture of Motul synthetic 2-cycle oil.

It appears I have fuel, spark and compression. SO WHY WON'T MY ENGINE START?????? ARRRGGGGHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!!!!!!

As I mentioned, it did run for a little bit two or three times yesterday when I first tried to get it going. It now won't even attempt to start. If I disconnect the plug wire and head down the road and try to start it, it sounds the same whether the plug wire is on or not, so obviously it isn't even attempting to start. I have been fooling around with this crazy thing for two days now and I am not happy. :(

Any suggestions?

andy b.
 
flybytaco

flybytaco

Metal Molding Madman
Oct 17, 2009
1,170
8
0
seekonk MASS
andy b. said:
Okay, I've been reading here all day and playing around with this engine. I found the specs to check the CDI unit and magneto resistance values, and they look good. If I put a sparkplug into the plug cap and hold it against the engine head while pedaling down the street I get a nice blue spark, so the ignition system seems to be working. I also pulled the magneto side cover off and all looks well in there.

Fuel flows in a nice stream out of the shutoff on the bottom of the tank, and if I pull the drain plug on the carb fuel bowl I get a steady stream of fuel out. If I run down the street a few times and let the clutch out to try and start the engine, and then pull the sparkplug, the plug is wet with fuel, so it appears fuel is making it to the engine. I have the clip for the needle on the stock middle position.

The engine seems to have excellent compression and I don't see any leaks from the head or exhaust or carb anywhere. I am using 89 octane gas and about a 16:1 mixture of Motul synthetic 2-cycle oil.

It appears I have fuel, spark and compression. SO WHY WON'T MY ENGINE START?????? ARRRGGGGHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!!!!!!

As I mentioned, it did run for a little bit two or three times yesterday when I first tried to get it going. It now won't even attempt to start. If I disconnect the plug wire and head down the road and try to start it, it sounds the same whether the plug wire is on or not, so obviously it isn't even attempting to start. I have been fooling around with this crazy thing for two days now and I am not happy. :(

Any suggestions?

andy b.
Click to expand...
and that motul isnt made to run 16:1 really go 32:1 that stuff is like red syrup cherry
 
A

andy b.

New Member
Jul 14, 2010
55
0
0
PA, USA
flybytaco said:
and that motul isnt made to run 16:1 really go 32:1 that stuff is like red syrup cherry
Click to expand...
You're right on the cherry syrup. :) Do you think that could be part of my problem? Like I said, I had a Banshee that I rebuilt and ran many years ago, but it ran good from the start, so I didn't have to play around with it much. I don't know if running to thick a mix will just foul the plug right out and stop it from running.

I think I'll pick up some new plugs and thin my mixture a little.


curve said:
We had a motor here recently that had a bad piston pin bearing and would not run for crap.
Click to expand...
Oh, that makes me feel real good. ;)

andy b.
 
A

andy b.

New Member
Jul 14, 2010
55
0
0
PA, USA
curve said:
I was just giving you another option. We ended up junking that motor for parts. It never ran.
Click to expand...
I know. I just thought it was a funny reply. :) I hope my problem isn't quite as serious, but I guess you never know until I keep fiddling with it.

andy b.
 
T

Tyler77

New Member
Aug 1, 2010
1
0
0
Saint Paul, minnesota
:-||Hello:) I just ordered a 66cc skyhawk and I pretty much have everything installed. But my clutch isn't working right. When I pull the lever and push the bike I can hear the engine compressing. And the pin that is on the inside doesn't seem like it is pushing in? It's like it is hitting something? Oh and I had one more question how long at a time can you run one of these?
 
KCvale

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
Is all that little 'push button' on the carb does is hold the float down.
That simply lets gas overflow the bowl into your carb (or even air cleaner).
Pumping it does nothing special other than give you a warm fuzzy feeling ;-}

This could be just as simple as flooding the motor with too much fuel.
A couple of seconds on the 'flood' push button and 1/2 choke is all you need to get it going if there is enough fuel in you fuel mix.

I am not familiar with that oil, but if it as dense as indicated as others say, cut it down or even just drain the system and try a fresh mix of fresh gas and cheap 2-stroke oil at the proper Grubee 18:1 break-in mix.

Then just keep pedaling.
Once you get her started keep running 1/2 choke for a few blocks before you push the choke levelr down and off.

Do NOT attempt to adjust your idle with the cable adjustment screws.
Pull off the air cleaner and work the throttle.
Watch the carb plunger and the cable ends.
The plunger should go up and fully down freely, use the cable adjustment to take any cable slack out as the end that goes in the carb top will tend to pop out and stay out if it is too loose (thus acting like sticking your throttle at 1/4 turn on).

Use the carbs set screw to adjust the idle, you can see this with the air cleaner off as well.
Just screw it until you see the plunger just start to rise, then you know where you are.
Leave the air cleaner off while you try all that out and test ride.

Now for idle it is very possible your clutch is not fully disengaging.
It doesn't take much drag to kill the motor at idle.
Considering the single gear ratio of a direct drive that will enable you to hit 30+ MPH you sacrifice the ability to 'putt along' under 10.
Even a 3-speed shifter solves that, I can putt along at 5 and topped 41 MPH yesterday on my first short run with regular 25:1 mix, and I know she has more in her ;-}

Get yourself familiar with where the idle adjuster is with your left while on the bike. Once you get it warmed up, 10 minutes or so and choke off, get a safe stretch of road you can go 15 or more on and get to that speed.

Lock the clutch in and see if dies.
If so, it is not clutch drag at 15 MPH, so give the idle screw a 1/4 turn and try again.
Once you get able to idle at 15 lock the clutch in and stop.
If it dies, adjust the clutch cable until it doesn't.

Once you get it to idle stopped with the clutch in, you can fine tune the idle speed with the idle screw while stopped.
Don't forget to put the air cleaner back on!
If that kills the motor you know what to took at.

Nothing like a nice quite smooth idle.
I get an almost sadistic pleasure from how quite and smooth the idle is on my shifter bike riding the canal bank paths.

There is a lot of Spandex on them and when I am cruising along at a leisurely 30 MPH and approaching one from behind I just lay off the throttle.
No need for the clutch, it has two freewheel coasters so it drops to idle but looses no speed.

I coast up next to them virtually silently, give the customary nods and say Hi, then lay on the gas and disappear. hehehehe ;-}
 
A

andy b.

New Member
Jul 14, 2010
55
0
0
PA, USA
Okay, today's update.

I drained the carb and fuel lines and mixed 1 gallon of straight gas with 1 gallon of my 16:1 Motul mix, so that should give me a 32:1 mixture. I then filled the bike tank with that.

I tightened up the clutch cable to be sure the clutch was fully disengaged when the clutch lever is pulled in.

I rechecked my wiring, and when turning the engine over with a plug in the plug wire and holding the plug against the engine, I get a nice blue spark.

I installed a new plug (a Bosch W7AC because that was the only thing anyplace around me had for sale that came up as a cross-reference for the NGK B6HS).

I tried pedaling down a hill in front of my house and letting the clutch out and kept pedaling, and still no luck.

Because now I was REALLY getting p!ssed, I noticed there was a slight bit of blow-by on the head right beneath the spark plug (at the head and cylinder mating surface). I think the engine should have ran like that, but I pulled the head off anyway and smoothed it on some 1000 grit sandpaper on a piece of plate glass I use to smooth things. I then re-installed the head and torqued the head studs to 15 ft-lbs. After trying to start it for another hour, there is no blow-by, so I fixed that problem anyway.

When I had the head off there was a lot of black oil on the cylinder and inside the head. I am guessing this is from the first few times the engine tried to run when I first installed it. It was pretty oily, so I definitely was running way too much oil in the mix. I wiped the top of the cylinder off, and inside the head before re-installing it.

Once I put everything back together I tried starting the engine at half choke and pushing in on the primer for a few seconds. I now see how that primer button works. If I hold it in too long the fuel will start running out of the primer button. The engine did attempt to run a few times, and after playing around for an hour and getting tired, the head and top of the exhaust by the head were slightly warm, so the engine was trying to run.

Now for a few more questions. Since I was running way too much oil, is it possible a bunch of oil is in the crankcase and still fouling my plugs? If so, should I just keep trying to start the engine with no choke, or with full choke?

It seems as though the engine really wants to run, but there must still be some stupid thing I'm not doing right. Regarding moving the c-clip on the needle. Before I do something, I like to know why I am doing it. When the engine is 4-stroking, you guys say to move the clip up one notch. If I understand what is going on, that would allow the needle to set deeper into the main jet and thus reduce fuel being drawn into the engine. Or am I not understanding how it works and moving the clip one notch higher allows more fuel in?

And finally, KC mentioned adjusting things with the air cleaner off. Should I take it off to see if it helps me at least get it running? I'm riding on a clean paved road, so I'm not real concerned with getting dirt into the engine for the short time the air cleaner will be off.

Any other tips or advice are appreciated.

andy b.
 
Mind_Reader7

Mind_Reader7

New Member
May 1, 2010
392
1
0
Northam, Western Australia.
Put the choke all the way on (if it's like mine, there's a hole in the middle, which gives it a good ratio anyway) and as your pedalling, open the throttle back and forth all the way as you try. It should sound like it's going to kick over, then put the choke off, and pedal/throttle up and down.
 
Bikeguy Joe

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
Try a few drops of fuel mix in the spark plug hole, and see if it fires better or worse. If it is better, choke it more, if it is worse, choke less. Just to be sure, choke on is up. I am not being patronizing, some get it backwards.
 
A

andy b.

New Member
Jul 14, 2010
55
0
0
PA, USA
Thanks guys, I'll try full choke and throttle wide open tomorrow. I wasn't sure if opening the throttle all the way would just flood it more or not.

Regarding the choke, yes, at first I didn't know if choke on was up or down. I pulled the air filter off to see if it maybe was blocked or something and when I did I saw how the choke works. It doesn't hurt to mention though that the lever up is choke on. Like you said, you never know if I knew that or not. If anyone else reads this hopefully it helps them.

One other thing, my carb is slanted. I tried to install the engine with the carb level, but there was no way to do it unless I put something like a 3" long front mount on the engine. The fact the spark plug was getting soaked with fuel, leads me to believe it is okay with the carb tilted, but I thought I'd mention it. If it really will cause a problem, I can just bend the intake, or notch it and re-weld it to make it level. Oh, by tilted I mean the front of the carb sits lower than the air cleaner end.

andy b.
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
The carb can stand a few degrees of tilt, but anything over 15 or so will cause issues with the float being able to properly control the fuel level inside the float bowl.
 
KCvale

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
Yes, you can test run it with the air cleaner off for a bit on pavement.
Also verify with the choke open that the carb slide moves all the way up and down properly.

It sure sounds like it is flooding with your plug so wet.
As GearNet mentioned, these engines will tolerate a few degrees of tilt, but with too much forward tilt you could very well have raw full coming up through the jet and into the motor, and even disrupting the venture effect that pulls the fuel up and atomizes it.
The fuel won't combust properly in raw form.

You might want to consider just leveling the whole motor up some.
gasbike.net sells the universal mounting kit for $15.
What I like is the extra long dual front studs and second front mounting block (middle if pic).



You could use the single bolt through front frame but I don't trust them.
Your motor is constantly wanting to turn left and that bolt will do little stop that.

With the dual studs you have one going down the right side of the frame and will counteract the motor pull.



They are going to sock you with shipping so you might as well get a couple other things that come in handy like a Trispark spark plug, gas cap, exhaust gasket, and since you had the head off, head gasket.

Or if you want you can get an assembled Keylock Ignition and Wiring Upgrade kit from me and I'll toss in an extra set of long studs and extra block I have in with it. You can reuse the rest of you front mount hardware with them.
 
A

andy b.

New Member
Jul 14, 2010
55
0
0
PA, USA
KC,

Thank you for posting that photo!!!!! I received an extra one of those mounting blocks and wondered why the heck it was included. NOW I understand how the extended mount works. I welded up a custom front mount for mine and it fits into the stock mount. By using that extension block I can still use my custom mount. It may be easier than I thought to get the motor leveled.

I have another question, but I think my tilted carb may be a big part of my problem. Anyway, my question is, can the timing ever be off on these engines? I know the magneto stator really can't move much, but the magnet on the end of the crank might move. I didn't look closely at it when I had the magneto side cover off, so I didn't look to see what type of key keeps it in place. I just thought I'd ask since you never know if that could also be a problem.

andy b.
 
You must log in or register to reply here.
Top Bottom