About to burn this bike to the ground

M

madscihighpsi

New Member
Background - I bought a kit about a year ago from a place that is no longer in business. It was a very simple very easy chinese kit. I had very very very little and few problems ran it for a year and after a few clutch adjustments something catastrophic happened with the clutch part of the engine and didn't want to buy a bunch of parts to fix it (couldn't split the case because the phillips head bolts were stripping.) I had just bought new wheels for the bike because the bearings were shot, I also bought new tires, and tubes.

To date - Rather than fixing the clutch I decided to buy a Grubee gt5 kit. This kit has given me nothing but ****.

The carb = no mid to high range, cannot go past mid throttle. More recently (3 miles on engine) it won't even idle anymore.

The chain - the cheap 415 chain was nothing like the 420 chain I had. I went to put the 420 chain back on tonight and because the other one just got f****d up. The tensioner was redrilled to mount to frame. THe idler pulley was ruined. Now the internal gear is making noise...

I am sick of this thing needed to vent and am about to throw it right under a street sweeper.
 
Don't toss it in a dumpster!

You got a year out of the last one... Once you get this one squared away, it will probably be as good or better!

Good luck
rc
 
The carb problem is as follows:

I have a 16:1 ratio of 2 stroke.

The carb idled fine for the first time I fired it up (it was night time probably 50-60*F) The idle was normal and fine with no adjustments. Then later I tried to adjust the screw and I cannot get it to idle correctly (with the chain popping off so frequently its hard for me to keep it running to get the carb able to be synced. The carb is sealed with permatex on the lip to make sure it seals.

The other problem is the throttle. My old bike I beat the crap out of it from day 1 opening the throttle to full position and it ran great the whole time I had it minus the clutch issues. The chain never had these alignment issues either until this new engine (didn't change the idler or rear wheel alignment.)
So I guess my carb complaint would be that I have no mid-high throttle can't get it going over 10 mph I am trying to be patient and gentle with this engine but its hard and frustrating. The e-clip is on the 2nd rung and I have not touched the jet because the mixture will be changed but I don't remember my old carb being this horrible with a slight change of mixture.

:-||
 
On a new kit, the Philips head screws commonly need to be loosened with a hand impact driver. The Chinese like to over tighten them for some unknown reason.
7 Piece Reversible Impact Driver Set

Never tighten them with an impact driver though. Hand tightening with a screwdriver is best. This will also let you loosen them easily in the future as well. Replacing all of them with Allen head screws is best though.
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A hardware kit will get you going in the right direction better and cheaper than any other way as all the factory screws and studs really should be replaced before an engine is ever installed in a bicycle. The Chinese are still learning what quality steel is. SBP kits are made with very good quality steel.
Sick Bike Parts
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What carburetor came with your GrubeeGT5? I searched them and found that it came with a NT carburetor but I'd rather ask you before assuming. Kit contents do change randomly.
Every carburetor that comes with every kit always needs tuning and tinkering to get them to work correctly. It is the nature of the beast when it comes to these cheap priced kits. It is easy to do though, don't get worried over that.
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The kit chains are made of recycled garbage metal. The best thing you can do with a kit chain is recycle it again using the trash can or local recycling center.
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The kit tensioners are usually garbage too. Most are solid plastic but a few kits come with the higher quality ball bearing tensioner wheels.
Either get a ball bearing tensioner wheel or make one out of a skate board wheel. If you go the skateboard wheel rout you will need a way to cut a perfectly round groove all around the middle of the wheel slightly wider than the chain. It needs to guide the chain, not just push up against it.
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Unfortunately a street sweeper will not help you fix any of these common problems.
Hopefully we can help you though.





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Last edited:
GearNut said:
What carburetor came with your GrubeeGT5? I searched them and found that it came with a NT carburetor but I'd rather ask you before assuming. Kit contents do change randomly.
Click to expand...

This one came with that red cover often referred to on here as the "speed carb"

Where do I pick up a better 420 chain? Also it came with a 415 chain can I put a heavy duty 420 one on it? I like that style because I can get the master links cheap at lowes.
 
Speed carbs and NT carbs are nearly identical.
This thread should go a long ways towards helping you out:
http://motorbicycling.com/f39/motorized-bicycle-carburetor-install-rebuild-302.html
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You can use a 415 chain like what I have now. I got a Tsubaki standard non o-ring chain from a local motorcycle accessory store for $20. I think it is overkill, but hey, it's bullet proof for what a 2 horsepower engine can dish out
You can also use a KMC410H bicycle chain. Most better bicycle stores that sell BMX racing products carry them or can order one for you. Expect to pay $15 or less.







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Ok, you do not have a Speed Carburetor. You actually have a CNSv2 carburetor.
They are the only ones that have the cable actuated choke.

In stock form, they are quite possibly the worst carburetor to come with the kits ever.
The good news is that other folks have figured out why they are sooo bad and what is needed to be done to them to turn them into really good carburetors.
Here's a link to that thread:
http://motorbicycling.com/f34/omg-i-have-tune-cns-help-30169.html

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All of these links I have posted for you I got by using the search function on this forum.
Have you tried using that yet?











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All of these I have read and seen before. I just have not quite dug into the carb/chain as much as I have wanted and was on a wrench throwing rant at the time of the post.
 
I completely understand. Sometimes you get soo pi$$ed that you want to kill it forever (street sweeper).
Just walk away from it and come back an hour or two later with a clear mind and fresh patience.
 
LoL

THIS, is what BEER is for!
Calms the nerves and allows you to sit back an consider things with patience.

...Just don't down a half dozen bottles of Dogfish Head Ale and get ON the bike!
like the jackass did in his porsche
rc
 
Well here is an update after taking a break and having a beer and a day to relax I decided to buy a new chain to work on the bike again. Well when I went to install the chain on the bike I installed it the way I was supposed to. The bolt loosened so I went and tightened the bolt a little and fought with it. I ended up installing the chain again and ended up stripping the bolt! I'm beyond pissed with this kit I could not get ahold of Kings Motorsports tech line because all day "their business hours were not on today." I can't believe that

Ok so I am coming from a Daemon kit which ran like a top for so long to this skyhawk kit gt5 which people on here seem to mostly own and I can't stand it so far.... Anyone else run into these troubles?
 
If you have the carb off your old kit try switching it on the new kit. If your engine revs you got one issue solved. If your kit requires the narrow chain go to a bike shop get a KMC 510 chain. It is narrower than the 415 chain but just as tough - it is the chain of choice for bmx racers.
 
Alright got a new bolt from hardware store. Then I got a new BMX chain and fired the bike up today. some of the kinks were worked out in the acceleration of the bike. Then once again I tried to take some slack out of the chain by removing a link and ended up breaking the chain completely. Tomorrow is a new day and I'm going to get a new master link.

Sidenote: No street sweeper in this bikes future for right now.
 
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