Rings

#1
I did use the search tool (for a whole ten minutes...not nearly as much patience for the web as for wrenching) and couldn't find the answer. I have a junk 2.8 that I have been playing with. I've heard they are t so bad when properly built. I'm gonna rejet with my pen vise and add some good oil, new spark plug, and I might even build a new exhaust. This will be basically free, so I'm not out anything other than time, and I call that garage therapy. I'm going to pull the head and check the rings and cylinder after I rejet. I want to try the rejet first. It will start and run, but it's rough. My question is about piston rings. It's a new style DB30, and I only want to buy rings, but I can only find them for the older style DB. I did find a kit for $90 that was almost everything but the crank and seals, but there's no way I'll spend that on this. I've got clones and Briggs sitting here as well, but I want to tinker with this. For. $90 I'll just stick the Briggs on and go. Anybody know where I can get a set of rings for around $15? I'm only checking because it smokes a little.
 
#2
Put some good oil in it and flush it a couple of x's until oil comes out looking clean. Drill out main jet next size, usually 76 (0.020). I have a bunch of these, never seen one yet that had worn rings. Most used ones have very little oil in them and what they have looks bad.

If you still need rings:

97cc 2.8 HP piston, rings.

I have one I did 5 diff mods to and runs very well IMO (rejet carb, black clutch spring, remove compression release, cut head 1cc, drill out muffler).
 
#3
Awesome! I'll try flushing it first. I got it in pretty rough shape. The carb was a mess. I finally got it running after tearing into the carb. I'll look into those clutch springs. I was thinking about cutting the muffler off of the header, and then putting a new pipe and silencer on. I'll see what happens. I need to start a thread for this build. Thanks again.
 
#5
Drill out main jet next size, usually 76 (0.020). I have a bunch of these, never seen one yet that had worn rings.
Okay, so I just got my mini drill set in the mail yesterday. I pulled the carb tonight to drill out the jet, and when I pulled it out, it was huge! I got the 61-80 set, and I could probably fit 2 or 3 of the 61 bits in the hole at the same time! It must have been drilled out by the previous owner. I bet this hole had a diameter of 1/16 or 3/32 of an inch! I'm assuming this is too much? I've got a new plug in it, and I've been running it without an air filter element (because the original was so caked with dirt that it wasn't usable) just to get it going. I'll pull the plug and look at it. I had it starting and running well tonight. As soon as I hit the throttle to rev it up, the motor died. Could this be because of two much fuel entering the combustion chamber when I hit the throttle? I was wondering if I may need to drill out the muffler to allow more flow since the jet is too big, or should I just buy a new jet? What is the stock size? I can drill the stock size, or maybe I should just order 76 (and maybe a size up and below the 76)?
 
#7
I just assumed it was the same jet as the one in the gx200/ clone carb. I was gonna order a number as close to the stock jet as possible, and then just drill out one size at a time. I may be way off, and maybe the jets are different, but they appear to be the same size diameter and thread pattern. I've got some old stock gx200 jets around, and maybe I could try one of them first? I don't know what the stock jet sizes are, so I guess I need to find that information out first, huh?
 
#8
Last time I looked, 6.5 clone carb main jet threads were larger diameter, won't fit 97cc carb (maybe wrong, but that's what I came up with).

I have Honda generator that has GX100 engine I bought jets for (different elevations for camping). I will check this weekend to see if same size. If so, can get from Honda for approx $5 a jet already drilled to size.
 
#9
I wonder if the g100 carb would have the same jets. the gx100 is an OHV motor, but the g100 is a flathead, according to someone on another thread. This might be the way to go. Anybody have any experience with this?
 
#14
Hello davidlamb78,

Try it before you drill out the main jet, it may run great as is. I recently bought 2 new looking carbs off CL, don't know where originally purchased, but both ran great no adjustments needed.

I leave the idle jet stock, seems to idle better. If idle is rich, engine pops at idle, but otherwise runs OK.

Test after engine is warm, with the choke off. Give it some gas, engine should make smooth transition to power. If engine hesitates, the main jet is probably too small.

If new carb, probably only need to drill out main jet. If used engine, and doesn't run well, could be other issues, such as: clogged fuel filter, inlet needle leaking, worn/ torn idle jet o-ring, contaminated fuel, dirty carb, dirty air cleaner, air leak, bad sparkplug, etc).

Sometimes a 97cc will wear me out, but after I get it to run really well I have a great sense of accomplishment. :thumbsup:
 
#15
My carb arrived on Friday. I put it on the motor today. I'm excited because it has the adjustable needle on it. My other carb didn't. I was able to get the motor fired up, and it ran for a few seconds. It wanted to die until I gave it some gas, and then it revved up. As soon as I let off the throttle it wanted to die. I'm assuming that the needle is not where it should be. I'did give it a few turns out, and it helped. Any suggestions as to where I should start with the needle? I think I might be close. I don't have the motor bolted to the bike yet. I am still working on the frame. It will be on there soon. I think I only need to get some wheel spacers to get it together. Then I can put the wheels on, get the motor on the frame, and get it going. It did run better than it ever has with the new carb, so I know that was the main problem. I knew the carb was a mess when I bought it, but I was trying to get it going for free. I had $4 credit on my amazon, so I got it shipped to the door for less than $10. I won't complain about putting $10 into the motor and getting it to run!
 
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