BY, curious what main jet you used and main nozzle?
BornYamaha
Member
I used the VM34-389 Like the one listed on Dennis Kirk as their # 1655. I had to get mine from Summit Racing since Dennis Kirk was out of them. They were cheaper anyway. I only changed the main and pilot to 230 & 35 going with the richer settings in the earlier posts to be safe to begin with. Once I encounter some cooler temps and do some more testing I may consider dropping a little leaner.
I may try this "Going to order a O-0 tube and 6DH4 needle here pretty soon and she should be about done." which was listed on page 6 later. It seems like it had a good outcome. I have raised my engagement and dropped my gearing one tooth so I am not running in the very low rpm range much. This setup adjustment may make it so some of these smaller jetting changes don't effect me as much as some. Below is the current jetting in the 250.
Main Jet: 230
Pilot Jet: 35
Air Jet: 0.5
Needle Jet: 159 Q-2
Jet Needle: 6DH2
Throttle Slide: 2.5
I may try this "Going to order a O-0 tube and 6DH4 needle here pretty soon and she should be about done." which was listed on page 6 later. It seems like it had a good outcome. I have raised my engagement and dropped my gearing one tooth so I am not running in the very low rpm range much. This setup adjustment may make it so some of these smaller jetting changes don't effect me as much as some. Below is the current jetting in the 250.
Main Jet: 230
Pilot Jet: 35
Air Jet: 0.5
Needle Jet: 159 Q-2
Jet Needle: 6DH2
Throttle Slide: 2.5
opsled
Active member
You would think as many times as this has been done and as many people that are out there saying how great this swap is that there would be a standard formula of what works but as always it's all over the map.
A guy on FB the other day was pulling his hair out over this. Had been through his carb multiple times. Finally after M-effing Yamaha and their junk carb he tossed it and the oil injection in the trash and went V roundslide because all the ET Larry followers told him to. Guess what,,,, same schnitt.
I asked him if he ever checked the crank seals. After I got chastised by the crank seal police about how then never go bad and I'm an idiot the guy checked them out and low and behold!!!!!!! His PTO crank seal was TOAST!!
These sleds ALL ran perfect when they were new with the parts they came with. Don't know why anyone would assume they are junk.
opsled
A guy on FB the other day was pulling his hair out over this. Had been through his carb multiple times. Finally after M-effing Yamaha and their junk carb he tossed it and the oil injection in the trash and went V roundslide because all the ET Larry followers told him to. Guess what,,,, same schnitt.
I asked him if he ever checked the crank seals. After I got chastised by the crank seal police about how then never go bad and I'm an idiot the guy checked them out and low and behold!!!!!!! His PTO crank seal was TOAST!!
These sleds ALL ran perfect when they were new with the parts they came with. Don't know why anyone would assume they are junk.
opsled
opsled, correct. The stock carb works fine, no reason to replace and lose the oil injection. And I agree on changing crank seals. These sleds are FORTY years old!
However, there were some sleds that ran terrible with the stock carb, like the butterfly carbs on stock 1980 SRX 440 for example.
However, there were some sleds that ran terrible with the stock carb, like the butterfly carbs on stock 1980 SRX 440 for example.
I would think a Q-2 would be rich for this engine and agree that an 0 series will be better. The best way to find the right setup would be to use an oxygen sensor in the exhaust.
opsled
Active member
There were other factors on the 80 SRX too. Many changes were made on an engine who's base in design was much different than Enticers. ET's and others were using butterflies for years without issue. There was never and recall or any other factory updates the correct problems with any Enticer carb as far as I know. Not so with other sleds that did have issues.
opsled
almost there
Maim,
Enticer 250 with the new mikuni really flys at top half of rpm spectrum. Starts every time with half a pull.
Coming off the line is the only problem left here. I read that this part of the range is related to the pilot jet and so I've been looking at ordering my next best guess. I now have a 30 pilot jet (with 220 main). It must be too small since it will not stall out the engine even with the air screw turned completely in. I see some other guys going with a 35 pilot. Any opinion on what size I should go with. Thanks again for the help. This is going to be a really nice sled. I have already swapped a 50 pilot back and forth with this 30 (which was the factory jet) but makes no difference.
Maim,
Enticer 250 with the new mikuni really flys at top half of rpm spectrum. Starts every time with half a pull.
Coming off the line is the only problem left here. I read that this part of the range is related to the pilot jet and so I've been looking at ordering my next best guess. I now have a 30 pilot jet (with 220 main). It must be too small since it will not stall out the engine even with the air screw turned completely in. I see some other guys going with a 35 pilot. Any opinion on what size I should go with. Thanks again for the help. This is going to be a really nice sled. I have already swapped a 50 pilot back and forth with this 30 (which was the factory jet) but makes no difference.
BornYamaha
Member
Quick Update - Tried the 0-0 tube and 6DH4 needle. It definitely did not take off as well at lower rpm. Tried original needle in the 0-0 tube. Maybe a little better than when paired with 6DH4 needle. Tried the Q-2 tube with 6DH4 needle. This seems to be the best combination I have. There could be a better setup, but I am leaving it like this. It works pretty good for me. The temp at the time was about 20* and my elevation is around 800 ft. I am also using the 35 pilot & 230 main.
Same boat
Born, So here I am with this same problem dogging out when coming off the idle to mid range rpm. Just so I know for sure... your "Q2" tube is referring to the needle jet in which the needle moves up and down. My needle jet (tube) is stamped with "159Q0". Is your tube then stamped just Q-2 or are there other numbers with it? I'm thinking that my problem lies more with the needle and jet rather than thinking that switching my 30 pilot to a 35 is going to be of any benefit. I'm not seeing anything by looking at spark plug either.
Born, So here I am with this same problem dogging out when coming off the idle to mid range rpm. Just so I know for sure... your "Q2" tube is referring to the needle jet in which the needle moves up and down. My needle jet (tube) is stamped with "159Q0". Is your tube then stamped just Q-2 or are there other numbers with it? I'm thinking that my problem lies more with the needle and jet rather than thinking that switching my 30 pilot to a 35 is going to be of any benefit. I'm not seeing anything by looking at spark plug either.
secondary
I'm being told to also check the secondary clutch belt position since this can cause very similar problem with low end bogging.
I'm being told to also check the secondary clutch belt position since this can cause very similar problem with low end bogging.
BornYamaha
Member
Hi Gary,
My Q-2 was what was originally in my new carb that I purchased. The specs on the carb stated that it was a 159 Q-2. It is very difficult for me to read even with magnifying glass. I was able to make out the 159 & the Q2 part on it so I have no reason to doubt the specs I was given. It is in the sled now. It can make some sense that a somewhat rich lower end can help the sled take off better. When racing other sleds in the past it was always a good plan to have a fairly rich pilot and a leaner main for best drag results. I have not messed with the other jets very much. The needle jet (Tube) is just above the pilot in the fuel circuits. I have attached a jet chart I found that shows where these are in progression. Mine definitely likes the Q-2 better with either needle I have.
After saying all this I would like to suggest changing the primary spring if this sled is not to be ridden by a child or timid rider. Mine now takes off really well with skis in the air if you want to. I am using the Blue-White spring from the attached chart and a couple shims in the primary. I did the math and the lower rate with the higher preload & the additional shims is almost exactly the full compressed tension with the stock spring. This really makes it take off great and also holds the RPMs a little higher when you are going slow. This spring has been out of production for many years but I had my local dealer do a search and he found one just last year at another dealer. Hopefully there are still some left. I also took my secondary apart this last weekend with the plan to add a little more twist to the spring. I figure that it has been in there for 41 year under tension so I am sure it has lost some of it's original value. I saw somewhere online that they had extra holes for adjustments just like the other Yamaha secondaries. I had never taken an Enticer secondary off or apart even though I had owned a few. Wow what an unbelievable pain in the A$$. Once I got it apart guess what. No extra holes. I drilled my own about 50* tighter than the way it was. I drilled an identical hole 180* across from the one I drilled for the spring just in case this small hole would effect clutch balance in some way. Probably not enough but I am a nut about that kind of thing. That seemed to be about right by some miracle. It backshifts better and brought my higher speed rpms up a little like I was hoping for. I have no tach so this is all by ear and feel. If this sled is for a beginner maybe you could try to find an original set of primary & secondary springs. I am thinking this is part of the problem. One more thing. These little 250s come geared to do between 60 & 65 MPH. That is higher that needed unless you are under 100 pounds and on a icy road. I dropped my top sprocket tooth down one and I still have a theoretical top speed of between 55 & 60 MPH. It all helps the little sled have a better chance. On a simpler note you do need to verify that your clutches move freely, rollers are good, & your belt is in spec like you mentioned before I wrote this novel.
Good Luck !
My Q-2 was what was originally in my new carb that I purchased. The specs on the carb stated that it was a 159 Q-2. It is very difficult for me to read even with magnifying glass. I was able to make out the 159 & the Q2 part on it so I have no reason to doubt the specs I was given. It is in the sled now. It can make some sense that a somewhat rich lower end can help the sled take off better. When racing other sleds in the past it was always a good plan to have a fairly rich pilot and a leaner main for best drag results. I have not messed with the other jets very much. The needle jet (Tube) is just above the pilot in the fuel circuits. I have attached a jet chart I found that shows where these are in progression. Mine definitely likes the Q-2 better with either needle I have.
After saying all this I would like to suggest changing the primary spring if this sled is not to be ridden by a child or timid rider. Mine now takes off really well with skis in the air if you want to. I am using the Blue-White spring from the attached chart and a couple shims in the primary. I did the math and the lower rate with the higher preload & the additional shims is almost exactly the full compressed tension with the stock spring. This really makes it take off great and also holds the RPMs a little higher when you are going slow. This spring has been out of production for many years but I had my local dealer do a search and he found one just last year at another dealer. Hopefully there are still some left. I also took my secondary apart this last weekend with the plan to add a little more twist to the spring. I figure that it has been in there for 41 year under tension so I am sure it has lost some of it's original value. I saw somewhere online that they had extra holes for adjustments just like the other Yamaha secondaries. I had never taken an Enticer secondary off or apart even though I had owned a few. Wow what an unbelievable pain in the A$$. Once I got it apart guess what. No extra holes. I drilled my own about 50* tighter than the way it was. I drilled an identical hole 180* across from the one I drilled for the spring just in case this small hole would effect clutch balance in some way. Probably not enough but I am a nut about that kind of thing. That seemed to be about right by some miracle. It backshifts better and brought my higher speed rpms up a little like I was hoping for. I have no tach so this is all by ear and feel. If this sled is for a beginner maybe you could try to find an original set of primary & secondary springs. I am thinking this is part of the problem. One more thing. These little 250s come geared to do between 60 & 65 MPH. That is higher that needed unless you are under 100 pounds and on a icy road. I dropped my top sprocket tooth down one and I still have a theoretical top speed of between 55 & 60 MPH. It all helps the little sled have a better chance. On a simpler note you do need to verify that your clutches move freely, rollers are good, & your belt is in spec like you mentioned before I wrote this novel.
Good Luck !
Attachments
BornYamaha
Member
Has Anyone that has done this conversion run down around 0 degrees or below safely with 230 or 220 mains? Reason I ask is I am going on a ride this weekend and unfortunately it sounds like it will be between -5*F and 0*F. I have the 230 in right now. I don't have any time on it below about 18*F.
Go up a size if you are concerned. When the weekend is over, observe the wash and spark plug colour.
1980 Enticer 250 well worth effort
Thanks for guiding me through this Mikuni swap project. The results are outstanding. I was able to get the job somewhat near satisfactory, but an experienced mechanic in Superior, WI dialed in the carb and adjusted the clutches in a way that I just could not. If someone offered me 4 grand for this sled right now I'd turn it down.
Thanks for guiding me through this Mikuni swap project. The results are outstanding. I was able to get the job somewhat near satisfactory, but an experienced mechanic in Superior, WI dialed in the carb and adjusted the clutches in a way that I just could not. If someone offered me 4 grand for this sled right now I'd turn it down.