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Discussion Starter #1
Guys,

A couple of quick questions.. i've just fitted a new engine but am waiting on a new chain as my current one is past its best, am i ok to run the engine without the chain fitted? i can't see this being an issue but did wonder if the bell or clutch could get damaged somehow when the clutch engages without the weight of the rear wheel/chain to turn. I just want to run the engine up and make sure everything is ok/set idle etc.

Secondly, this engine has a two piece head kit, and a nasty looking chinese 'race plug'. will either my bm6a or bpm7a work with this head kit or do i need a different type?

Lastly! On a new engine should i be sanding the clutch shoes/bell housing for more bite or is it only once i've used it abit i need to worry about this?
 

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If your head came with a racing plug...Keep using the racing plug

Its ok to start up the bike and run it without a chain...Just dont rev it too high and let it idle the first 10-15 minutes to heat cycle it....You should also use a fan as a cooling aid...

I always sand my bell and pads to dull whether its new or old..................Slippage creates heat..
 

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Discussion Starter #3
cool cheers Cam, i did your carb slide mod aswell so looking forward to testing that, i always thought the slide was plastic until i saw that thread lol.. sanding the bell/clutch pads will give me something to do whilst waiting for the new chain!
 

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Well, things are happening for you, Glad to hear it. Did you leave the base gasket out, and seal the base of the cylinder?? I like these 2 pc alloy heads, have like 4 now. I always break in the engine w/ the china plug, then change after the rings have sealed or it fouls.
New chain on that engine would be a plus. Did you get a FC crank kit, the stock cranks won't take much abuse.
I took a 16mm Walbro off my second new Sam's 3rd Stage Cag engine w/ 12mm FC crank, don't know if it was the carb, could not get it to adj. and the engine was not running right so I changed carbs, won't know till tomorrow when its finished.
Stole the 14/14 Dell SHA copy carb off Sam's Red stocker kit engine, and put it on the 3rd stage, to see if it is a carb problem.
 

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Well, things are happening for you, Glad to hear it. Did you leave the base gasket out, and seal the base of the cylinder?? I like these 2 pc alloy heads, have like 4 now. I always break in the engine w/ the china plug, then change after the rings have sealed or it fouls.
New chain on that engine would be a plus. Did you get a FC crank kit, the stock cranks won't take much abuse.
I took a 16mm Walbro off my second new Sam's 3rd Stage Cag engine w/ 12mm FC crank, don't know if it was the carb, could not get it to adj. and the engine was not running right so I changed carbs, won't know till tomorrow when its finished.
Stole the 14/14 Dell SHA copy carb off Sam's Red stocker kit engine, and put it on the 3rd stage, to see if it is a carb problem.
Youre a madman EPR.............lol..Keep up the good work...

I kind of feel that you may have a coil thats getting weak and still beleive that a wt603 even a wt813 is way too small for Sams 3rd stage power.....You definately need a HDA-48 w/external purge port..They come on the GSR45cc and Skopod 62cc engines....
 

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That's why I changed carbs, if it still runs like that, will start looking at the coil & stuff, the coil could have come loose it would not be the first time. Have a new Cag coil here. My A1 w/ Sams 3 stage engine runs so good w/ his Swirl Bored 14mm carb. His other carb is on my A2 B/B engine, the one I left the base gasket out. I wanted to steal that carb but it runs too good. Could not believe how much that eng changed by loosing .020" in cyld height. Its like a whole different engine, of course its been ported & modded all over that helps too.
 

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Discussion Starter #8
Well, things are happening for you, Glad to hear it. Did you leave the base gasket out, and seal the base of the cylinder?? I like these 2 pc alloy heads, have like 4 now. I always break in the engine w/ the china plug, then change after the rings have sealed or it fouls.
New chain on that engine would be a plus. Did you get a FC crank kit, the stock cranks won't take much abuse.
I took a 16mm Walbro off my second new Sam's 3rd Stage Cag engine w/ 12mm FC crank, don't know if it was the carb, could not get it to adj. and the engine was not running right so I changed carbs, won't know till tomorrow when its finished.
Stole the 14/14 Dell SHA copy carb off Sam's Red stocker kit engine, and put it on the 3rd stage, to see if it is a carb problem.
EPR i've cheated abit, i bought a complete engine already built up as it only cost me £60 (about 100 usd) however the disadvantage is that i don't know the true spec, it was listed as 49cc race engine, 2 piece performance head kit with perfomance piston and windows, uprated coil, race plug, lightened crank (whatever that means), toughened front sprocket and metal pull start and metal pawl, all colour coded red which goes with the colour scheme i'm planning. I haven't opened up this engine, just checked all the bolts and fitted it to the bike, the only thing i changed is to put the best quality carb i have on with a couple of little mods -petcock mod, inlet and out let polished but not ported, cams slide mod, tapered needle on 2nd notch, .70 main - as the engine came with a lame quality stock carb.

So i am still running the base gasket, if i lost it i'd need to raise the exh port etc accordingly as far as i'm aware, and don't fancy doing this/don't have the tools to atm!

I hope this should be enough for now and be a noticeable difference over my slightly knackered 47cc! Although it was a bit of a PITA to start last night.. though i'm hoping this is to do with the 25:1 mix and getting used to the extra compression/metal pull start - i broke two of the plastic pull starts so am a little paranoid about them now!

What plug do you replace the china one with once its fouled up?
 

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Discussion Starter #9
Guys, i've ran the engine up tonight and all good, seems like it has a shedload more power than the old engine just by revving it on the stand! lots of vibration!! :cool:

i have one little problem though, out of a matter of interest i used the needle that came with the carb the engine was supplied with first just so i could see the difference, this needle was stock with the clip in the 3rd position, with this needle it had rubbish throttle response as expected but idled ok, i then changed the needle for my tapered one with the clip in the lowest position, its now fine from a throttle response point of view but won't idle? the idle screw has no effect at all and if i let go of the throttle it'll just die..
 

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Sounds like youre overfuelling ..............Pull the plug to see what the real deal is.........

If you added any bbk other than Sams and havent reworked the components to work like they should that extra power you feel free-revving can sometimes turn into lowend bog and load-up when ridden......
 

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Get a 17:1 head piece, Dave's had them for .50 cents and put that in there, and put 2, .020" copper base gaskets under the cylinder if you have to much compression, that will raise your exhaust port, and with the 17:1 pc it will end up like 15:1. I just got my hydraulic Cag brakes, they are nice, both sets for $50 w/ my discount @ PB Parts in Florida and they ship international too. If you order there base gaskets they are .010", stock is .020" and them paper ones like my MBPN kit had or .025", I thru it away, and Yamabonded it to the engine. But I also moded my 3 intake ports and raised and widened the exhaust port, ground a flat spot on the piston top and some other small things.
 

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Discussion Starter #12
Guys,

Looking at the plug and the oil being spat out around the exhaust gasket i think it was overfuelling! Cam did you find that when you did the piston slide mod you had to move the clip up the needle? Obviously having the clip on the lowest grove made it overfuel and its now on the 3rd grove up (middle) and seems good and idles nice but the idle screw is only 3/4 of a turn from being fully in, i don't see this as a problem did you find the same? I've been trying to work out why the slide mod might mean the clip needs to be higher and how it effects the fuelling but havent satifised myself with a reason yet! I used to run the clip on one grove from the bottom with the standard slide and with the idle screw not so far in.

Also i think it might be time to change the plug already, it looks like some of the material from the tip of the plug has jumped over to the metal :confused: sorry for the lack of technical names, i'm talking about the two parts you set the gap between! Surely this can't be right? Can i fit my BM6A or BPM7A plug to a BBK engine? it's just the thread looks quite abit longer on the stock chinese plug? I'll get some pics up tomorrow.
 

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Seems weird that with the piston bottom modded that you would need to raise the piston that far w/ the idle screw. Maybe its still sucking to much gas or not enough???
It's alway a good idea to have a new or almost new plug to change. Both my 3rd stage engines, fouled the plug alot when they where new. I thought something was wrong with the engine & a new chinese plug made it all better. Still want to try The E3 plugs.
Some of my 49cc old finned head B/B 2 pcs kits had a long thin plug, same as my X18 110cc 4 stroke Honda clone engine. I believe Sams 3 stage kit head uses the short fat plug like the Cag.
 

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When I did my mod I had to lower the idle screw almost half a turn and raise the c-clip 1 notch.......

The new velocity that gets pulled through there actually pulls more fuel through the same jet than before the mod...........
 

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Gee, the way EPR is going on his engines, I don't know whether I should send an engine to be rebuilt to him or Sam ....
 

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Discussion Starter #16
Haha, yea i love cam's tips/mods as most of them are things i can do with a fairly basic tool selection, he also has pictures of everything lol :cool: i guess poor ol' boosted is so busy making the forum faster that he doesn't have time to post aswell!

Guys i think i've worked out the odd change in the idle screw whilst sitting here at work.. i have 3 carbs, one has some slight differences over the other two and is definately of better quality which makes it my prefered carb, i think what i've done is used a slide from one of the other two when i did the mod incase i messed it up, and my better carb must have a slightly different idle screw, either in length or where it contacts the slide, so i'll change the screw over and see what happens.

Thanks for the plug info EPR, i have a new NGK BM6A and a nearly new BPM7A. If boosted uses the stubby ones then i guess thats the BM6A, so that should be fine, but yea the original plug does seem alot longer, i wonder if this will effect the compression. Annoyingly the chinese plug is also gold instead of silver, which i find makes it harder to see the actual colour of the plug when you pull it!
 

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Sam, has a day time job, and works long hours sometimes, and does our engines on the side.
SpyGuy, send your engine to Sam, I use his mods as a guide line, the engines I am making our out on the edge. They are mostly experiments, and if nothing else I learn what Don't Work,lol.
The Blue Demon engine is waiting for the test stand, then it going back in the Lucky 7. Sams engine in it now, goes to the two engine project.
Has anyone ever noticed how thick the Cag 40mm, 40cc cylinder walls are. I got an ADA 2 pc alloy head, and ADA 40cc cylinder, with the thick walls I can put a deep wide 3rd port.
KevinT was talking about using an 40mm one ring piston from an RC engine in a 40mm cag cylinder. A GS460 piston or something, wrote it down, have to find it.
 

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Discussion Starter #18
Guys, i've put my new chain on last night, spent ages lining the wheel up right and making sure i got the L7's removable swing arm back on right. However i have a question! i replaced the old chain as it had had a decent amount of use and had what i thought to be quite a tight spot - the bike had been sitting in a shed for 2 years prior to be buying it so made sense - however when i put the new chain on it's just the same! should the chain have exactly the same slack all the way round or do all chains have areas that are tighter than others? i'm thinking of turning the chain to its tightest point and then adjusting from there, but then i'm worried this may cause too much slack on other parts of the chain?
 

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Discussion Starter #20
Ahhh dammit hadn't even thought of that!! i checked the sprocket to make sure it wasn't bent but never thought of it being ovaled!! Just ordered a new rear sprocket, cheers chimp!
 
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