Author Topic: 81 CM400T No more backfire! (Read 17217 times)

snowcase · « **Reply #25 on:** April 06, 2010, 07:06:57 PM »

The jets are supposed to be 72 and 118 like I have. I took everything apart, cleaned it and put it back. I'll be getting a new fuel line tomorrow to see if that keeps the fuel flowing freely. The piece that might be missing is on page 204, picture 17c of the clymer. It is the pilot cap. It does not look like what is in the manual. On the right carb there is something that is similar but protrudes (is not recessed like the picture) and on the left carb it looks like it was broken off.

snowcase · « **Reply #26 on:** April 07, 2010, 07:38:14 PM »

Rode it about 40 miles today. Only had a high idle a few times. I changed the oil today and now it's difficult to shift into neutral with the engine on. Gear changes are much more firm. I thought it might be because I added a little bit too much oil so I drained some and that helped a little. I may drain a little more tomorrow and see if that helps as well.

I attached a new fuel line. It didn't help the high idle. I'm noticing a slight tick in the left cylinder. There is also a large leak in the mufflers. I notice it coming out of the left side more than the right.

The pilot screw IS broken off on the left carb. I don't know how to get it out or where to get a replacement.

Johnie · « **Reply #27 on:** April 08, 2010, 06:15:05 AM »

It sounds like you are making progress. You probably had a few issues going on at once. You are slowly making things in order. That pilot screw could be causing you some problems if the previous owner screwed it all the way in and then broke it off. I have never seen that before. If I recall correct there is a spring and rubber seal on the end. The Honda manual says the pilot screw should be 1 to 1 1/2 turns out from lightly seated. If it is all the way in that could cause some running issues too. You may want to consider trying www.hondatwins.com It is a site specifically for the Honda twin and those guys work on them all the time. As far as the stiff shifting that could be caused by the type oil you put in too. But I take it you did check the owners manual for the right visocity and used motorcycle oil. Since I sold my last 400 twin I have been out of that scene for a bit. Just keep at it and remember...it is a hobby. Have fun with it.

snowcase · « **Reply #28 on:** April 08, 2010, 06:37:08 AM »

I've been on hondatwins a lot but I cannot register. I've tried contacting people on there to see if they can get in touch with an admin who can help me out but no luck.

Alan F. · « **Reply #29 on:** April 08, 2010, 08:21:54 PM »

Can't register eh? try www.hondatwins.net also.

snowcase · « **Reply #30 on:** April 08, 2010, 08:25:55 PM »

I was able to register today. Thanks for the help guys.

snowcase · « **Reply #31 on:** April 10, 2010, 06:59:36 AM »

I took the carbs completely off and apart. Cleaned everything I could and put them back on. No more backfire and much smoother idle and response. I would say it purrs now.

Johnie · « **Reply #32 on:** April 10, 2010, 07:13:55 AM »

Just like I said in an earlier post, right? Nothing like clean carbs to take care of the problems. Now that wasn't so bad to take those off and now you are an expert in that area and can help others. The 2nd time they even come off faster. So what did you do with the broke pilot screw?

snowcase · « **Reply #33 on:** April 10, 2010, 07:19:31 AM »

Haven't been able to do anything yet. I tried to match the other side as best as I could but I can't find a replacement screw anywhere.

Here is my post from hondatwins.net

I took the carbs completely off and apart to clean them thoroughly. I took lots of my own pictures this time.

- Changed the 2 adjusting arms. Both were way off.
- The right carb bowl was dry
- Both floats had a little orangish, tannish substance caked around the top. Bad gas?
- The air valve (I think is what it is. On the side of the left carb) is very, very dirty.
- Everything is relatively clean. The dirt from the pictures is mostly from the outside.
- What do the "nozzles" circled below do? Fuel came out of them.

snowcase · « **Reply #34 on:** April 10, 2010, 07:33:06 AM »

It's hard to tell with a cell phone but there's a significant difference.

Before cleaning and adjusting. Notice how high the RPMS are when I push in the choke
[youtube=425,350]9JqBlvuSkwY[/youtube]

After. Sorry for the night time shot
[youtube=425,350]YyfmC5vQhdg[/youtube]

snowcase · « **Reply #35 on:** April 10, 2010, 08:44:45 AM »

Should be all good now.

Johnie · « **Reply #36 on:** April 10, 2010, 10:08:14 AM »

I can not tell how far down the pilot screw is broke off. You might be able to cut a slit in what is left there and get a screwdriver on it. There should not be that much tension on the screw that is left as there is a spring and rubber washer on it as I recall. You could try a Dremel to cut the slit but you might cut a bit of the bowl as well. Or maybe a punch of some kind to make a slit in it. I wonder if tapping a screwdriver end on there could give you enough bite to get it out.

snowcase · « **Reply #37 on:** April 10, 2010, 10:15:46 AM »

I considered a dremel but it's too far in. I'll need a tap of some sort.

Johnie · « **Reply #38 on:** April 10, 2010, 04:26:41 PM »

If you tap a few times with a screwdriver do you think it would make enough of a indent that you could back it out?

Alan F. · « **Reply #39 on:** April 10, 2010, 06:36:14 PM »

Maybe you could file two angled faces onto the tip of a small screwdriver....kinda like a two fluted endmill except in the reverse direction?

That way giving the driver a light tap will help the tip to dig into the screw, and turning the screwdriver will only seat the tip tighter into the grooves it cuts.

Anyone get what I mean?

Johnie · « **Reply #40 on:** April 11, 2010, 04:47:43 AM »

Quote from: Alan F. on April 10, 2010, 06:36:14 PM

Maybe you could file two angled faces onto the tip of a small screwdriver....kinda like a two fluted endmill except in the reverse direction?

That way giving the driver a light tap will help the tip to dig into the screw, and turning the screwdriver will only seat the tip tighter into the grooves it cuts.

Anyone get what I mean?

Sure...I think that is a good idea.

snowcase · « **Reply #41 on:** April 13, 2010, 04:58:37 PM »

Quote from: Alan F. on April 10, 2010, 06:36:14 PM

Maybe you could file two angled faces onto the tip of a small screwdriver....kinda like a two fluted endmill except in the reverse direction?

That way giving the driver a light tap will help the tip to dig into the screw, and turning the screwdriver will only seat the tip tighter into the grooves it cuts.

Anyone get what I mean?

I sort of understand. I'll have to give it a try. First I need to fix the clutch cable my friend decided to pull apart.

I tried to clean up the engine. Anyone know a way to get it shiny? I want to paint it in the future.

Before

After

BlindJoe · « **Reply #42 on:** April 18, 2010, 01:24:46 PM »

So you want to get it shiny and then paint it

What parts do you want shiny/ painted?

snowcase · « **Reply #43 on:** April 18, 2010, 01:26:12 PM »

Shiny=Clean. Gotta be clean to paint it.

BlindJoe · « **Reply #44 on:** April 18, 2010, 01:31:03 PM »

you want to paint it while its in the frame? the whole thing? one color? If you'd explain more in depth of what you want to do it'd be easier to help

snowcase · « **Reply #45 on:** April 18, 2010, 01:37:18 PM »

No. I want to get it clean this summer then over the winter take everything apart and paint it. I was looking for suggestions on methods of cleaning it.

BlindJoe · « **Reply #46 on:** April 19, 2010, 01:33:09 PM »

gotcha, well if you're going to be riding during summer/fall it wouldn't make to much sense to clean it now since you'd just have to clean it again come winter, plus you'll have an easier time and the ability to do a more thorough job cleaning it out of the frame.

here's a link to a search on engine painting http://forums.sohc4.net/index.php?action=search2;params=YWR2YW5jZWR8J3wwfCJ8YnJkfCd8MTEsMiwxMTMsMTAzLDU5LDU0LDEwLDEsMjYsMjUsMjQsMzQsNTAsMzMsNDUsNTUsNDcsNTYsNTcsNTIsNTgsNDQsNCw5OSwxMDIsMjksMTA1LDYwLDYxLDEwNyw2MiwxMTYsMTE0LDk2LDgxLDksMTEyLDExNSwxMTcsOTcsMywzMXwifHNob3dfY29tcGxldGV8J3x8InxzdWJqZWN0X29ubHl8J3x8Inxzb3J0fCd8cmVsZXZhbmNlfCJ8c29ydF9kaXJ8J3xkZXNjfCJ8c2VhcmNofCd8cGFpbnRpbmcgZW5naW5l

BlindJoe · « **Reply #47 on:** April 19, 2010, 01:36:33 PM »

and cleaning http://forums.sohc4.net/index.php?action=search2;params=YWR2YW5jZWR8J3wwfCJ8YnJkfCd8MTEsMiwxMTMsMTAzLDU5LDU0LDEwLDEsMjYsMjUsMjQsMzQsNTAsMzMsNDUsNTUsNDcsNTYsNTcsNTIsNTgsNDQsNCw5OSwxMDIsMjksMTA1LDYwLDYxLDEwNyw2MiwxMTYsMTE0LDk2LDgxLDksMTEyLDExNSwxMTcsOTcsMywzMXwifHNob3dfY29tcGxldGV8J3x8InxzdWJqZWN0X29ubHl8J3x8Inxzb3J0fCd8cmVsZXZhbmNlfCJ8c29ydF9kaXJ8J3xkZXNjfCJ8c2VhcmNofCd8ZW5naW5lIGNsZWFuaW5n

snowcase · « **Reply #48 on:** April 20, 2010, 11:15:52 AM »

Searching... Never would have thought of that. Thanks for the help.

Alan F. · « **Reply #49 on:** April 21, 2010, 07:30:27 AM »

Quote from: snowcase on April 20, 2010, 11:15:52 AM

Searching... Never would have thought of that. Thanks for the help.

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Author Topic: 81 CM400T No more backfire! (Read 17217 times)

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