joe wiseguy intake

Quick and easy question, will the joe wiseguy xs6t0 intake bolt onto an xs400? I'm frankly done with trying to fiddle with two carbs. What a stupid setup, and needless hassle of I can simplify to one carb.

No. Do a search of the forum for 2-1 carb setup. These type motors don't work well with this setup as they have a 180* crank. They will run but tend to have a hanging idle and one piston will run hot.

So it doesn't physically fit?

I've done the search - given the crank, they have a weird pulse, but jetted and spark-plugged correctly, I'm not sure what the problem is - the cylinders only run one carb at a time anyway. If you go with an offset intake, the length of runners should help to compensate the lean left cylinder further.

Those that have fabbed up a single carb intake (from what I've read on here) seem to like it, and it certainly simplifies tuning and modifying.

I'm just ready to have this thing running, and having rebuilt the carbs more times than I can count, I'm done with pulling and tearing down two carbs repeatedly. I've synched them using the trans fluid method, I compensated the new exhaust (to replace the rusted out trumpets) with richer jets, and I've tested the float level in both repeatedly. There is not a single blessed reason why this thing doesn't want to run that I can figure. It has new plugs and wires, both are sparking, and the system registers about 13 volts when I do get it to run. It bogs, it has a sky high idle at times, and for all intents and purposes goes between exhibiting too rich or too lean, depending on the mood its in. I'd think sticking float, but I've ensured that not to be a problem, having tested both for hang and free-ness, and the entirety of the pair of carbs has been boiled out, first in bar-keeper's friend, and then in white vinegar and water to get rid of any remaining varnish. I blew all the passages out with carb cleaner, and ensured that everything appears to be working correctly.

I can rebuild a computer-controlled quadrajet in my sleep. These two glorified lawnmower carburetors are giving me fits.

To answer the question on the wise guy thing, no xs650 stuff will not work. The spacing is not the same. As for the one carb thing, if it was an easy well working long term solution to the xs400 we would all be running them. On your currant setup, the more mods from stock you go the more changes you will need to do for a proper tune. Have you replaced you butterfly seals? That can cause a lot of issues. Also is the rest of the motor and ignition in good tune. The carbs are only part of the equation.

Butterfly seals haven't been replaced but appear in good shape and don't cause a vacuum leak when tested with starting fluid at the shaft ends. I have new plugs and wires, both are sparking, charging system registers about 12.7v when running, and is steady from wherever I can get it to idle to 5000+rpm. Engine has even compression on both sides and doesn't have leak down based on checking with engine oil. Tested valve lash and it's within spec.

So far, the only thing I did as far as modifications is to rebuild the carbs and replace plugs and wires, add glasspacks and swap the jets to compensate. I don't remember what they were swapped to...give me a sec...

45 pilot and 137.5 Main in both carbs for the jetting

When you take out your idle air mixture screws, do they have 2 tapers? If you only see one, then make sure the second taper isn't broken off and stuck in the carb body. Apparently they tend to snap and get stuck due to over tightening. Words come from an ex-yamaha mechanic that worked on them when they were new.

They have 2 tapers. Backed out 3.5 turns. I've tried everywhere from 2 to 5 turns out - not enough change to matter - boggy.

I just pulled them apart again, took them down to the bodies and butterflies (left them connected to prevent having to re-synch them), and now for some crazy reason it won't start. Wouldn't start before - flooded enough to backfire and set the air cleaner manifolds on fire...Did that bad boy again. Lots of fun!

Have you ever tried it with the stock jetting? Did you replace the o-rings for the mix screws? There should be a o-ring, washer, spring then needle. Also make sure the needles for the needle jets (the ones in the slides) are assembled correctly. I have seen a lot of people install them in the wrong order making the bike not run. Shorty glass packs are not great mufflers for tuning. A lot of issues with them.

Mickey85 said:

Butterfly seals haven't been replaced but appear in good shape and don't cause a vacuum leak when tested with starting fluid at the shaft ends. I have new plugs and wires, both are sparking, charging system registers about 12.7v when running, and is steady from wherever I can get it to idle to 5000+rpm. Engine has even compression on both sides and doesn't have leak down based on checking with engine oil. Tested valve lash and it's within spec.

So far, the only thing I did as far as modifications is to rebuild the carbs and replace plugs and wires, add glasspacks and swap the jets to compensate. I don't remember what they were swapped to...give me a sec...

Click to expand...

These bikes should run 14.5-7 volts at 5k rpms.

Needles are assembled correctly. I went with the stock jets, and then up a size. It doesn't seem to make much of a difference. The o-rings are present and don't appear to be cracked. I'll pull them again and see what's up.

I'm getting what seems to be conflicting symptoms though - it's lean enough that it doesn't run under 5,000 RPM (idles there, in fact), but rich enough to backfire flames out of the exhaust. At least, I'd assume that that represents a rich state - excess fuel in the exhaust...

Also, the voltage is with a super quick read immediately after startup due to the crazy excessive backfiring making me nervous about self-destruction...

God I'm fat...that's where I am at the moment. It pops at idle when warm too but I didn't catch it. Throttle response is ok, and it seems to run as it should, backfiring aside...started without choke.

Btw, at 5k rpm the voltage at the battery is 13.8

The factory carbs are crap. The Honda guys always make fun of them. Sudco will sell a new set up specifically made for the xs400, will run around $350. Cheapskates on this board think that is outrageous, but what is that compared to a non running bike that has been worked on constantly to no avail? If you want to keep experimenting try a carb set up from a ninja 500, might be referred to as an EX500. Those carbs are modern and a virtual bolt on. Don't let the experts tell you the ninja carbs wont work. They have do and will. Good luck

Mickey, flames out the exhaust is most often the sign of a very lean mixture. What color are the flames? Blue-white (lean) or yellow-orange (rich)?

ksrebel, that is some tough talk. Especially from a 2.5 year/10 post member. Do you have anything to contribute other than insulting other members here? Have you done a carb conversion?

Mickey85 needs to know there are other ways of solving the problem. Only he can determine what his time is worth and it is valuable.. There are instances when components become unfixable. Who knows what a previous owner may have done, like drilling out carb passages. If the carbs are unfixable, explore other alternatives.

Dave, looked orange to me, and it's now started bogging like it's rich. Sigh...

Ksrebel, the carbs are 100% stock, as is the rest of the bike. It was bought new in 81, maintained by the dealership, and parked in 1987. Its been a bear resurrecting it, as I've been fighting varnish and crud the whole way. I should have gotten it running right with the original exhaust before swapping, but one of the mufflers was rotten all the way around the header anyway. I went up a jet size both pilot and main, and it still doesn't seem to do right.

I am fighting what seems to be a losing battle here. It has gone from high idle and lean to bogging and rich from one start to another without changing anything else. I'm about to just take it to the dealer and have them shoot it.

I've been contemplating older style carbs, but given that these are original and unmolested, getting new ones seems to be adding another tuning problem

Plug missing/fouled, out of sync carbs, out of time or bad ignition box, low compression or valve not sealing. Any of these things can cause that to happen. For the bs34 carb haters, I run all three versions of these (76-82) in my three bikes and they all work great. The ex500 carbs have been used on the xs650 for a while with good results with only having to mod them a little.

Did you clean the tank? Have you installed a fuel filter? If it runs lean then rich with no changes, you might be pushing crud thru the system.

Thank has been cleaned and boiled. Running an online filter and clear gas line.

Plugs have been checked and both spark, compression is in the 140s on both cylinders. It doesn't change much when I put oil in the cylinders (under 10 psi). Have yet to check timing because honestly this is the best it's run so far, and I'll synch the carbs as well. Hope to do that tomorrow

My last shot with first hand knowledge. Check the coils. A misfiring coil can be mistaken for fouled carbs.