I recently purchased an unmolested 70 xlch. It has a Screamin' Eagle carb on it that I cannot find parts for, and Iam replacing it w/ a 92 Keihin CV that will have a Stage I upgrade to it.. I am a novice, and getting back in to bikes and the mechanics of them, so I need help, and any information on this conversion would be greatly appreciated.

The bike runs good, and kick starts easily w/ theSE, but when I put a load on it or really get on the throttle, it bogs down in the midrange. I found out the SE was an add on for an 80cu engine. This is a 900 Sporster,55cu engine andthe SE carbmay be too much for it. I also found out they are veryhard to tune.

1.) The CV has 2 vacume ports on it. Where do they go when you retro this to an old Ironhead, or just plug them?

2.) I am putting baffles in the drag pipes that came w/ the bike prior to changing the carb. I know it will effect the tuning.

I plan to keep the bike stock in looks, and performing well andwithin my budget. I cannot afford an S & S upgrade, etc.

Any help, sugestions, or links to CV retrofitto anIronhead sites are greatly appreciated

Thanks-Steve

 

Nice bike! The vacuum ports are probably for a VOES and a vacuum-operated petcock (although I think these actually came out a year or two later than '92), or the second one could actually be an overflow tube. If they are vacuum ports, just cap both of them. You'll need a later model air cleaner to fit the carb flange if you want to keep the ham can ( I would, for the stock look), a mainfold adapter, and some sort of new support bracket. There's a how-to on http://www.sportster.org/tech/carb/cv-fe.shtml, but it's an older writeup and uses a funky air cleaner adapter/bracket. You're right, the SE carb you have is probably too big.

 

Thanks, I am lovin' this thing. It really caught my eye when I first spyed it.

I believethe one on the bottom to be an overflow tube. There is also an adjustment screw that is confusing, right near where the overfow comes out of the body.I dolike the ham can AC I have. I will work to kee it, andhope to keep it so it looks stock. I have a manifold adapter comming, it's apress fit mount rather than a rubber mount w/ clamp. I have seen the article. It is definitely a resource.

Thanks for the cmpliment and the response-Steve

 

I think that HD did away with the mag ignition on the 70 model. Are you sure that is a 70?

Pinion Gear, can you help out here?

 

Positive. Numbers match on the bike, and coordinate w/ the Sporster.org website numbers. No mag on this thing. I am trying to retrofit the Keihin CV to this Ironhead for better performance w/ a stock look.

Thanks, Steve

 

They did get rid of the mag in '70, but Steve's bike has the external timer with the points inside that mounts where the mag went. Same setup the XLH had for years. In '71 the case changed to the same styleused today.

 

|Steve
I have that carb on my 79xls, the AC bracket is just flat bar bent and connected from engine to aircleaner. The problem I had, was it just stuck out too dang far, unlike the S&S. I love the carb and have had no trouble out of it except that at idle it runs a mite too rich. Too compensate for the size I replaced the tank but it still gets in my way on the highway pegs. I kept the stock tank and fenders and all but I really do like the bigger tank and dash. Nice looking ride enjoy Dusty

 

The XLH model has always had a distributor, power supplied by battery.
The XLCH is the only model to have had a magneto. The CH came equipped with a magneto in 1969, the last year for it to have one.
In 1970 both models came with a distributor, located in the side of a new timing cover, under the round cover plate.
Previously, the distributor on an XLH had sat on top of the timing cover while the magneto on the CH sat in the same location.
The 1970 model big news of the day was the new distributor. The 1970 still had the old dry clutch.
1971 brought the new wet clutch, and this was a very welcome change. 1971 was the last year of 55 inch (900cc) displacement engines. 1972 the engine was enlarged to 61 inches (1000cc).
For carburation, the 1970 model would have come with a Tillotson or 'Model HD', as Harley liked to call it. It was not a very good carb at all. I had one on my 71 and I gave the thing away early on. The Bendix carb followed on the 1972 model and it was a much, much better carb.
If someone wants to install a replacement carb on the Sportster then the Bendix is a good choice and is most likely the least expensive of choices.
The Bendix uses a butterfly, they are still made and are simple. Parts are available for them as well............pg

 

Thanks for all the info. I wanted to post an update to my problem.

I did purchase a set of 4" baffles for the drag pipes, and I installed them last weekend. I was not able to test ride it until later that week and WOW! It was the missing back pressure that was creating my bog down when I put the throttle to it. It now runs better than adequate. I bought a helmet, licenced it and have taken it on a couple hour ride each day last weekend and it ran great. Starts easy also (kick only.). I am pleased it finally runs like I thought it would when I first spied this thing. It's not perfect, but it sure is cool, and there is not another around here like it.I will retro the CV to it later, as for now I am going to ride it and explore NM while I am at it! I've been trouble shooting it since the purchase in late August. It's nice to see a bit of troubleshooting, and $15.00 worth of parts can rectify an anticipated $300-$500 uneeded carb upgrade.

Sharing the success.
Steve

 

Glad to hear the bike is running well. Yes, the baffles do make a difference. The normal open drag pipes (40 inch long) provide enough back pressure, but adding baffles give it a bit more. Now there is a trade off of course (there are no free lunches here) and that is the back pressure will hurt the top rpm.
But most of your running is not at top end (I hope!) so it is a good compromise.
I once had a two into one set of pipes on my Sportster a long time back. The two pipes dumped into a 4 inch diameter end pipe that had a large baffle in it. It ran OK. Then I removed the baffle and the bike was dead on the low end. When I ran it up to top end however, the Sporty would fly. It took a couple of days to get the rpm up to 6600 though, or so it seemed. Yeah, drag pipes with baffles are the way to go with an old ironhead.
Thanks for giving us the update..........pg