Carb Trouble 1971 XLCH
#11
Join Date: Aug 2006
Location: 500 miles south from Artic Circle
Posts: 751
Likes: 0
Received 6 Likes
on
5 Posts
As PG wrote... do one thing at one time !
Keihin is just fine carb, just go and buy repair kit for it that includes all what you need.
S&S is cheap, but in my opinion it's meant for dragracing and it's not so good even for that.
Newer Keihin CV from some evo model is cheap (used) and good carb, you may get one from ebay or swap by 30-50USD. It works better than S&S or old keihin.
Some may say that Mikuni VM38 is the best... I have Mikuni HSR42, but that is $$$.
If you put other carb than original you need make some modifications to bike: S&S and CV needs double throttle cables. Mikuni and CV needs flange adapter. There might be clearance issues with petcock and fueltank also how to route throttle cables.
Keihin is just fine carb, just go and buy repair kit for it that includes all what you need.
S&S is cheap, but in my opinion it's meant for dragracing and it's not so good even for that.
Newer Keihin CV from some evo model is cheap (used) and good carb, you may get one from ebay or swap by 30-50USD. It works better than S&S or old keihin.
Some may say that Mikuni VM38 is the best... I have Mikuni HSR42, but that is $$$.
If you put other carb than original you need make some modifications to bike: S&S and CV needs double throttle cables. Mikuni and CV needs flange adapter. There might be clearance issues with petcock and fueltank also how to route throttle cables.
#12
You said you just want to get it running to check for other problems, buy a $20 kit for the keihin and go from there. I have no problems with my keihin on my 79, works great. AND pay attention to pg's posts, he's been there, done that, knows his s--t. With PG on one side and Ironmike on the otherside you can fix any Ironhead out there. (I think anyways) Ride safe.
Last edited by 1200efi; 12-30-2009 at 05:34 AM.
#13
I personally would run a Bendix over a Keihin any day. On my '77 I run an old S&S Super B and love this carb. Older used Keihin have always been more trouble than they are worth in my opinion. I've gotten better performance and better tuning out of a Bendix. A Mikuni is also a good choice of an upgrade for a carb.
#14
#15
I would rebuild your Keihin as my first choice now.
If you need (or want) another carb then a used one is OK, but be prepared to at least put a kit into that.
Sorry to mislead you about buying a Bendix. I had no idea we have had that much inflation this past decade.
pg
#16
#17
#18
I had a Keihin acting the same way, after soaking and new kit in it,was still at the point of turning the idle mixture screw out 5 1/2 turns. The low speed jet was packed full of melted rubber, the only thing that would clear it was a drill bit. I believe the wonderful fuel we get here in Florida was dissolving the fuel lines an packing the jets shut. After drilling out, the carb tuned as it should, actually not a bad carb now.
#20
Here's my carb cleaning notes for Keihin butterfly style carb ...
1. Removing it from the bike should be straight forward. First thing when it is out is to check the pilot screw setting. Turn it all the way in until gently seated counting the number of 1/4 turns; then write this number down; then reset it.
2. I put mine in a vice to remove the screws, and for much of the following work. Wrap in a shop towel; close the vice gently taking extra care with the choke and throttle linkages. The vice is a needed extra pair of hands.
3. You must be very careful handling the float so as to not change the level. You must have the official specs for setting the level as in the FM, and check it, every time you dismantle the carb, as the last thing before putting it back together.
4. The jets are made of brass, a soft metal that is easily damaged. Use an exact correct size screwdriver. I ground a medium flat blade screwdriver down to exact size on my bench grinder to access the slow jet.
5. The general appearance of the inside of the carb is not necessarily a good indication of its condition. It can look spotless and have clogged jets, or look cruddy and have clear jets.
6. Ignore any advice that says to soak or boil the whole carb in carb cleaner. Rather, clean each individual part. Do not allow any solvents to contact any rubber parts [tip of needle, o-ring seal for bowl]
7. Make a list of all of the jets and passages for your carb using the carb manual or the FM for the bike. Then ensure that you can blow either compressed air or carb cleaner thru each one.
8. Remove the pilot screw and clean the parts and the passage. The passage contains in this sequence: pilot screw, spring, washer, o-ring. These are very small parts, especially the washer and o-ring. Usually the spring will easily fall out. One time i thought the spring was not in there because it would not fall out; i obtained a new spring and could not get it in! The technique for removing the washer and o-ring is to use a pipe cleaner: stick it in the hole, twist it around, remove it - you should see the washer and o-ring on the end of the pipe cleaner.
Remember that the purpose of the washer is to protect the o-ring from the spring and you will always get them back in in the correct sequence.
9. Dismantle the accelerator pump assembly noting carefully the sequence and orientation of the parts. Clean and inspect the parts. Replace the diaphragm if it is cracked.
10. Check the float level then carefully put it back together. I personally find it very confusing trying to decide which way to bend the tang if it is not correct. If the fuel level is low is the float high or low? Do i need to bend the tang up or down? On the bench the carb is usually upside down, adding to the confusion. Sort all this out before making an adjustment.
Best to replace the original Phillips screws for the bowl with stainless steel socket head screws.
1. Removing it from the bike should be straight forward. First thing when it is out is to check the pilot screw setting. Turn it all the way in until gently seated counting the number of 1/4 turns; then write this number down; then reset it.
2. I put mine in a vice to remove the screws, and for much of the following work. Wrap in a shop towel; close the vice gently taking extra care with the choke and throttle linkages. The vice is a needed extra pair of hands.
3. You must be very careful handling the float so as to not change the level. You must have the official specs for setting the level as in the FM, and check it, every time you dismantle the carb, as the last thing before putting it back together.
4. The jets are made of brass, a soft metal that is easily damaged. Use an exact correct size screwdriver. I ground a medium flat blade screwdriver down to exact size on my bench grinder to access the slow jet.
5. The general appearance of the inside of the carb is not necessarily a good indication of its condition. It can look spotless and have clogged jets, or look cruddy and have clear jets.
6. Ignore any advice that says to soak or boil the whole carb in carb cleaner. Rather, clean each individual part. Do not allow any solvents to contact any rubber parts [tip of needle, o-ring seal for bowl]
7. Make a list of all of the jets and passages for your carb using the carb manual or the FM for the bike. Then ensure that you can blow either compressed air or carb cleaner thru each one.
8. Remove the pilot screw and clean the parts and the passage. The passage contains in this sequence: pilot screw, spring, washer, o-ring. These are very small parts, especially the washer and o-ring. Usually the spring will easily fall out. One time i thought the spring was not in there because it would not fall out; i obtained a new spring and could not get it in! The technique for removing the washer and o-ring is to use a pipe cleaner: stick it in the hole, twist it around, remove it - you should see the washer and o-ring on the end of the pipe cleaner.
Remember that the purpose of the washer is to protect the o-ring from the spring and you will always get them back in in the correct sequence.
9. Dismantle the accelerator pump assembly noting carefully the sequence and orientation of the parts. Clean and inspect the parts. Replace the diaphragm if it is cracked.
10. Check the float level then carefully put it back together. I personally find it very confusing trying to decide which way to bend the tang if it is not correct. If the fuel level is low is the float high or low? Do i need to bend the tang up or down? On the bench the carb is usually upside down, adding to the confusion. Sort all this out before making an adjustment.
Best to replace the original Phillips screws for the bowl with stainless steel socket head screws.