Mike,
Thanks for your response. I will try the things you wrote later this week when my parts get here. I jumped the gun and tore the upper end of the engine back apart already. I don't know what I will do with my spare time after this bike is fixed, I sorta look forward to working on it now. I still have cosmetic things, paint and chrome to fix and then the bike will be done. I will post a message later this week and let all know how it comes out.
From: Mike Gladu <mgladu@mindspring.com>
To: Honda-C70@yahoogroups.com
Sent: Tuesday, July 26, 2011 11:40 AM
Subject: Re: [Honda-C70] Re: Top Speed Issue
At 6:02 AM -0700 7/26/11, Charles Schlosshan wrote:
>A, Thanks for your suggestions and I will try and answer them.
>- Tire pressure is 35psi
>- Oil is 10W-40 motorcycle oil and the oil pump is operating.
>- Brakes and chain are correct. Chain and sprokets are new. Gas is
>fresh this week.
>- Carb is new and jets have been checked and cleaned. Air filter
>has been blown out and looks fine. A new filter should be here
>this week.
>- Tuning has been done over and over. Ignition timing is advanced a
>little just because the bike runs better that way. Carb is perfect,
>no bogging at all.
>- Cam timing is on the marks.
>- Smooth level road, there are a few here, is where I can get
>35-37mph. I usually set upright as do most scooter riders here. I
>come from the sport bike crowd so lying down on the bike is
>possible. CBR1000RR. One member suggested setting the point gap at
>the upper end of the adjustment span (.018mm) and give the condenser
>more time to recharge. I did this, was .012mm, and gained the
>additional 2mph I didn't get before.
>- Throttle cable has a little more play then 5mm; visual inspection
>shows the slide completely opening the carb throat. I will adjust
>it when my parts arrive.
>- Clutch is new and does not slip. The bike will almost do a
>wheelie when shifting to 2nd gear with the revs up.
>- Since the previous owner apparently never changed the oil I don't
>think it has had any slippery crap in it.
>
>I and running out of things to check/replace/repair so any
>suggestion would be appreciated. I tried to check the muffler for
>flow just using my hand. Hardley anything comes out the end at idle
>and not much more rev'ed up a little. The muffler was rusted anyway
>so I ordered a new one from Beatrice Cycle along with a new cylinder
>head. I think one of my valves may have been leaking a little. I
>could detect a little puff sound around the head that I would have
>called a burnt valve if it was a car. Anyway that is the last item
>I can replace on the upper end. The engine feels like it is trying
>to rev on up in third gear, sorta like a surge for a second or so.
>(?) I would think that would be the ignition timing but I have
>moved it everywhere possible to move it. A little advanced is where
>it runs the best. With the timing set on the F mark it runs really
>sluggish. Any Comments?
I would:
Put the ignition timing back 'on the marks' to have a better idea of baseline.
Change to a new condenser and points (if you haven't already).
Do a compression test (looking for better than 125psi).
Set the float level higher (as high as it will go without overflowing
on the sidestand).
Go to 40psi (can't hurt).
Make sure the chain has some free play (too tight will cause drag).
Spin the wheels off the ground to be sure the bearings aren't trashed.
There are a few pages in the online manual that take you through
every obvious and not so obvious step of troubleshooting slowness.
Check them out.
http://autos.groups.yahoo.com/group/Honda-C70/files/C70%2080-81%20Passport%20Shop%20Manual%20%28JPEG%29/172.jpg
http://autos.groups.yahoo.com/group/Honda-C70/files/C70%2080-81%20Passport%20Shop%20Manual%20%28JPEG%29/173.jpg
http://autos.groups.yahoo.com/group/Honda-C70/files/C70%2080-81%20Passport%20Shop%20Manual%20%28JPEG%29/174.jpg
Mike G.
-
[Non-text portions of this message have been removed]
1970-73 C70 Honda Service Manual: http://tinyurl.com/6ebwtw
1970-73 C70 Troubleshooting Guide:
http://tinyurl.com/6ebwtw (scroll to sec.7.1 page 101.jpg)
1980-83 C70 Honda Service Manual: http://tinyurl.com/hu42c
1980-81 C70 Troubleshooting Guide:
http://tinyurl.com/hu42c (scroll to sec.18-1 page 170.jpg)
1982-83 C70 Troubleshooting Guide:
http://tinyurl.com/hu42c (scroll to sec. 20-28 page 205.jpg)
1980-81 C70 Maintenance Schedule: http://tinyurl.com/z4zn6
1982-83 C70 Maintenance Schedule: http://tinyurl.com/hw35c
More resources for C70 Passports and Cubs:
http://www.shlaes.com/Vehicles/Scooter.htm
http://www.velodrome.com/HondaC70/HondaC70.html
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