1969 Honda CL350 Doesn't Go Above 40mph

nomorespameventhoughthejapanesespamgivesmeachuckle wrote:
> My brother-in-law recently acquired said bike.
>
> It wasn't running when we got it, so we cleaned up the carbs, changed
> the plugs, redid the exhaust gaskets, and touched up other
> miscellaneous ends.
>
> Both carbs are running and the pressure out of the exhaust pipe is
> even.
> The bike is loud but that's probably normal on this kind of bike.
>
> Unfortunately we can't get the bike to go above 40mph and I know this
> bike should do about 100mph.

It will have trouble doing 100 mph if you drop it out an airplane. 80
mph would be a bit more realistic. 40 mph is way to slow though as you
noticed. I have a 350SL.

1st guess: If they are CV carbs, the ones with the big piston attached
to a rubber/silicon gasket on top, they are leaking. Could be cracked
rubber or just put together badly. What happens is they won't open fully
and act like a restriction/choke. You should be seeing some soot on the
plugs if this is the case. Cracked rubber is a heart breaker if that is
the case and you don't have a time machine that can take you back to
1969 handy.

2nd guess: Whatever type carbs, the high speed jets are malfunctioning
for one reason or another. Could be plugged, could be needle retaining
set up isn't doing its job, could be wrong jet.

3rd guess: Restricted gas flow. Just happens to drip into the carb q.s.
to get to 40 mph.
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

Rick Cortese <ricortes DeleteThis @earthlink.net> wrote:

> 1st guess: If they are CV carbs, the ones with the big piston attached
> to a rubber/silicon gasket on top, they are leaking. Could be cracked
> rubber or just put together badly. What happens is they won't open fully
> and act like a restriction/choke.

This was my feeling, having had exactly this problem on a Z400 twin a
couplew of years ago. Itwent happily up to 70mph, and then refused to go
any faster, no matter what I did to it.

>You should be seeing some soot on the
> plugs if this is the case.

No, you won't. Because all that's happening is the slides aren't opening
fully. It's not like an additional restriction is being put in place.

>Cracked rubber is a heart breaker if that is
> the case and you don't have a time machine that can take you back to
> 1969 handy.

Actually, here in the UK we have NRP Carburettors (Google for them) who
replace diaphragms. They also do an export service. I've used them, as
have loads of posters on ukrm, and their service is *awesome*. Prices
are good, too - Kawasaki wanted £140 for a new pair of slides for the
Z400. NRP replaced both diaphragms for about £60.

You do have to send them your existing slides to allow them to do the
repair, though, which means a turnaround delay, but the quality of the
job and the price makes up for it.



--
Trophy 1200 750SS CB400F CD250 Morini 500 Sport
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5 The bells, the bells.....
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

The Older Gentleman wrote:
> Rick Cortese <ricortes.TakeThisOut@earthlink.net> wrote:
>
> > 1st guess: If they are CV carbs, the ones with the big piston attached
> > to a rubber/silicon gasket on top, they are leaking. Could be cracked
> > rubber or just put together badly. What happens is they won't open fully
> > and act like a restriction/choke.
>
> This was my feeling, having had exactly this problem on a Z400 twin a
> couplew of years ago. Itwent happily up to 70mph, and then refused to go
> any faster, no matter what I did to it.
>
> >You should be seeing some soot on the
> > plugs if this is the case.
>
> No, you won't. Because all that's happening is the slides aren't opening
> fully. It's not like an additional restriction is being put in place.
>
> >Cracked rubber is a heart breaker if that is
> > the case and you don't have a time machine that can take you back to
> > 1969 handy.
>
> Actually, here in the UK we have NRP Carburettors (Google for them) who
> replace diaphragms. They also do an export service. I've used them, as
> have loads of posters on ukrm, and their service is *awesome*. Prices
> are good, too - Kawasaki wanted £140 for a new pair of slides for the
> Z400. NRP replaced both diaphragms for about £60.
>
> You do have to send them your existing slides to allow them to do the
> repair, though, which means a turnaround delay, but the quality of the
> job and the price makes up for it.
>
>
>
> --
> Trophy 1200 750SS CB400F CD250 Morini 500 Sport
> GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
> BOF#30 WUSS#5 The bells, the bells.....

I think I've found the problem. The air filters on the carbs (one for
each side) are very dirty and grimy. To the touch they leave a heavy
oil residue on the hands. We are going to try to get replacement
filters for them on Monday; if we can't get any what is the best way to
clean these out? I'm guessing that compressed air won't do the trick
because of the oily aspect of the contaminant, so what would clean the
oil out if need be? To envision the air filters, they look like black
cylindrical foam pieces that attach to the carb's air-intake with
clamps.
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

nomorespameventhoughthejapanesespamgivesmeachuckle wrote:

> I think I've found the problem. The air filters on the carbs (one for
> each side) are very dirty and grimy. To the touch they leave a heavy
> oil residue on the hands. We are going to try to get replacement
> filters for them on Monday; if we can't get any what is the best way to
> clean these out? I'm guessing that compressed air won't do the trick
> because of the oily aspect of the contaminant, so what would clean the
> oil out if need be? To envision the air filters, they look like black
> cylindrical foam pieces that attach to the carb's air-intake with
> clamps.

I would use kerosene to cleaner the dirt out of the filters, then
re-oil them with
foam filter oil or engine oil.

When foam gets old, it deteriorates and falls apart. That's why K&N
cloth filters are better.
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

nomorespameventhoughthejapanesespamgivesmeachuckle
<nousenetspam.DeleteThis@gmail.com> wrote:

> I think I've found the problem. The air filters on the carbs (one for
> each side) are very dirty and grimy. To the touch they leave a heavy
> oil residue on the hands. We are going to try to get replacement
> filters for them on Monday; if we can't get any what is the best way to
> clean these out? I'm guessing that compressed air won't do the trick
> because of the oily aspect of the contaminant, so what would clean the
> oil out if need be? To envision the air filters, they look like black
> cylindrical foam pieces that attach to the carb's air-intake with
> clamps.

AS FB says, paraffin (kerosene) or petrol, and lightly re-oil before
refitting,. But new ones would be better.

However, just take it for a very short run without the air filters
fitted. For a mile or two it won't harm it, and if there is an immediate
performance increase, you'll know the air filters are the cause.

Mind you, they sound like they need replacing anyway.


--
Trophy 1200 750SS CB400F CD250 Morini 500 Sport
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5 The bells, the bells.....
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

The Older Gentleman wrote:
> nomorespameventhoughthejapanesespamgivesmeachuckle
> <nousenetspam.RemoveThis@gmail.com> wrote:
>
> > I think I've found the problem. The air filters on the carbs (one for
> > each side) are very dirty and grimy. To the touch they leave a heavy
> > oil residue on the hands. We are going to try to get replacement
> > filters for them on Monday; if we can't get any what is the best way to
> > clean these out? I'm guessing that compressed air won't do the trick
> > because of the oily aspect of the contaminant, so what would clean the
> > oil out if need be? To envision the air filters, they look like black
> > cylindrical foam pieces that attach to the carb's air-intake with
> > clamps.
>
> AS FB says, paraffin (kerosene) or petrol, and lightly re-oil before
> refitting,. But new ones would be better.
>
> However, just take it for a very short run without the air filters
> fitted. For a mile or two it won't harm it, and if there is an immediate
> performance increase, you'll know the air filters are the cause.
>
> Mind you, they sound like they need replacing anyway.
>
>
> --
> Trophy 1200 750SS CB400F CD250 Morini 500 Sport
> GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
> BOF#30 WUSS#5 The bells, the bells.....

I think we'll try and clean the filters with some kerosene and petrol.
We live in Iowa and I'd hate to have a small piece of dirt or stone
from the gravel roads get taken up the air intake and make itself into
the engine and ruin a piston. We'll try this Monday night (if we can't
get new ones).
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

nomorespameventhoughthejapanesespamgivesmeachuckle wrote:

> I think we'll try and clean the filters with some kerosene and petrol.
> We live in Iowa and I'd hate to have a small piece of dirt or stone
> from the gravel roads get taken up the air intake and make itself into
> the engine and ruin a piston. We'll try this Monday night (if we can't
> get new ones).

Methinks you worry too much.

If you are really really really worried about a bit of grit getting to
the piston, cover the carburetor inlet with some window screen.

Many years ago, before there was motocross, racers used to run their
engines with no air filters at all on dirt tracks, scrambles tracks and
even on beaches and dry lake beds.

The top piston ring is usally chrome plated on older machines before
about 1993, and they were able to survive season after season of racing
without damaging the pistons or evn showing appreciable wear to the
cylinder bore.
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

FB wrote:
> nomorespameventhoughthejapanesespamgivesmeachuckle wrote:
>
> > I think we'll try and clean the filters with some kerosene and petrol.
> > We live in Iowa and I'd hate to have a small piece of dirt or stone
> > from the gravel roads get taken up the air intake and make itself into
> > the engine and ruin a piston. We'll try this Monday night (if we can't
> > get new ones).
>
> Methinks you worry too much.
>
> If you are really really really worried about a bit of grit getting to
> the piston, cover the carburetor inlet with some window screen.
>
> Many years ago, before there was motocross, racers used to run their
> engines with no air filters at all on dirt tracks, scrambles tracks and
> even on beaches and dry lake beds.
>
> The top piston ring is usally chrome plated on older machines before
> about 1993, and they were able to survive season after season of racing
> without damaging the pistons or evn showing appreciable wear to the
> cylinder bore.

I thought the entire piston was extruded out of aluminum; that combined
with Iowa's dirt roads didn't sound like a good combination for me.
Didn't know the history concerning dirt bikes; how well did the bikes
hold up? Just because they did it doesn't mean that it didn't cause
dedgratation issues. I think we'd like to try to minimize any excess
wear on this bike seeing as it is over 30 years old already, extendind
the life as far as possible; though I might be talking out of
ignorance. We'll see what happens on Monday concerning acquiring new
filters. I do like your idea of the window screen =).
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

nomorespameventhoughthejapanesespamgivesmeachuckle wrote:

> I thought the entire piston was extruded out of aluminum.

A Pasta-Matic extrudes soft pasta dough into clever noodle shapes.
Though I suppose it would be possible to extrude aluminum pistons
through a steel die, the pure aluminum would probably be so soft the
piston wouldn't hold its shape under the high temperatures and
accelerations (about 4000 X the force of gravity) stopping at the
bottom and tops of the strokes.

Pistons are cast of an aluminum alloy that contains copper and silicon
and other metallic elements to make the piston stiffer. If you really
want a stron piston, a softer aluminum is cast and then forged under
high pressure with a set of dies.

> that combined
> with Iowa's dirt roads didn't sound like a good combination for me.

We are really only recommending that you try running the engine without
the air filters for a short time to eliminate the old foam filters as a
possible induction tract restriction. We aren't saying to go out and
run in a scrambles race with no air filters.

> Didn't know the history concerning dirt bikes; how well did the bikes
> hold up? Just because they did it doesn't mean that it didn't cause
> dedgratation issues.

The need for air filtration depended upon exactly what the race was all
about. Like, there were up to 1000 motorcycles starting in desert races
in the 1960's, but they were usually 2-stroke machines. Dirt in the air
would get down into the crankcase and destroy the needle bearings in
the rods.

But a 4-stroke engine just blows the air through the top end of the
engine. I could even make the argument that a small amount of dust
blowing through the top end would help seat the piston rings. After
all, old time mechanics knew about the Bon Ami cleanser trick. They
would dribble a handful of kitchen cleanser through the carburetor of
an engine with piston rings that failed to seat.

> I think we'd like to try to minimize any excess
> wear on this bike seeing as it is over 30 years old already, extendind
> the life as far as possible; though I might be talking out of
> ignorance. We'll see what happens on Monday concerning acquiring new
> filters. I do like your idea of the window screen =).

Well, it's your machine and it's up to you what you want to do with it.
We don't think that running without air filters for a few miles to
prove whether or not the pods are a problem, unless the miles you are
riding
are behind somebody throwing a cloud of dust into the air.
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

FB wrote:
> nomorespameventhoughthejapanesespamgivesmeachuckle wrote:
>
> > I thought the entire piston was extruded out of aluminum.
>
> A Pasta-Matic extrudes soft pasta dough into clever noodle shapes.
> Though I suppose it would be possible to extrude aluminum pistons
> through a steel die, the pure aluminum would probably be so soft the
> piston wouldn't hold its shape under the high temperatures and
> accelerations (about 4000 X the force of gravity) stopping at the
> bottom and tops of the strokes.
>
> Pistons are cast of an aluminum alloy that contains copper and silicon
> and other metallic elements to make the piston stiffer. If you really
> want a stron piston, a softer aluminum is cast and then forged under
> high pressure with a set of dies.
>
> > that combined
> > with Iowa's dirt roads didn't sound like a good combination for me.
>
> We are really only recommending that you try running the engine without
> the air filters for a short time to eliminate the old foam filters as a
> possible induction tract restriction. We aren't saying to go out and
> run in a scrambles race with no air filters.
>
> > Didn't know the history concerning dirt bikes; how well did the bikes
> > hold up? Just because they did it doesn't mean that it didn't cause
> > dedgratation issues.
>
> The need for air filtration depended upon exactly what the race was all
> about. Like, there were up to 1000 motorcycles starting in desert races
> in the 1960's, but they were usually 2-stroke machines. Dirt in the air
> would get down into the crankcase and destroy the needle bearings in
> the rods.
>
> But a 4-stroke engine just blows the air through the top end of the
> engine. I could even make the argument that a small amount of dust
> blowing through the top end would help seat the piston rings. After
> all, old time mechanics knew about the Bon Ami cleanser trick. They
> would dribble a handful of kitchen cleanser through the carburetor of
> an engine with piston rings that failed to seat.
>
> > I think we'd like to try to minimize any excess
> > wear on this bike seeing as it is over 30 years old already, extendind
> > the life as far as possible; though I might be talking out of
> > ignorance. We'll see what happens on Monday concerning acquiring new
> > filters. I do like your idea of the window screen =).
>
> Well, it's your machine and it's up to you what you want to do with it.
> We don't think that running without air filters for a few miles to
> prove whether or not the pods are a problem, unless the miles you are
> riding
> are behind somebody throwing a cloud of dust into the air.

I was wondering if the pistons were put though a cast process or
extruded, and working primarily with housings for AC motors at a local
company I picked extruded (that's what the company does for the
housings). I understand that extruding would require a softer metal
and that makes sense that you wouldn't want to extrude a piston.

So here's my concensus:

It's probably not a blockage in the exhaust because the pressure feels
(with my hand) the same out of the ends of both pipes. It would be a
mighty coincidence that both jets are bad in both carbs. It seems
probably that it is the air filters because both are in poor quality.
Am I right to come to these conclusions?

Thanks for all your help. Let's wait until Monday to see if we can get
some new filters before we start exploring our two-minute filterless
option =)... though maybe we should check before we go for parts since
it's an hour trip and it would be nice to consolidate the trips if we
find out we need a different part.
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

nomorespameventhoughthejapanesespamgivesmeachuckle wrote:

> It's probably not a blockage in the exhaust because the pressure feels
> (with my hand) the same out of the ends of both pipes. It would be a
> mighty coincidence that both jets are bad in both carbs. It seems
> probably that it is the air filters because both are in poor quality.
> Am I right to come to these conclusions?

If the pods are not plugged up, that leaves torn diaphragms in the
carbs or stuck piston slides or
plugged up idle mixture passages or a plugged up idle jet.

Motorcycles that had ignition points suffered from dirty pitted points,
and occasionally somebody would manage to install the points cover so
it grounded out the ignition on one cylinder.
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

FB wrote:
> nomorespameventhoughthejapanesespamgivesmeachuckle wrote:
>
> > It's probably not a blockage in the exhaust because the pressure feels
> > (with my hand) the same out of the ends of both pipes. It would be a
> > mighty coincidence that both jets are bad in both carbs. It seems
> > probably that it is the air filters because both are in poor quality.
> > Am I right to come to these conclusions?
>
> If the pods are not plugged up, that leaves torn diaphragms in the
> carbs or stuck piston slides or
> plugged up idle mixture passages or a plugged up idle jet.
>
> Motorcycles that had ignition points suffered from dirty pitted points,
> and occasionally somebody would manage to install the points cover so
> it grounded out the ignition on one cylinder.

I'm almost positive that this bike has ignition points, which I know
nothing about, so I'll have to do some research on this. What is the
housing for the ignition points called? There is a line that goes into
this housing on his bike that leaks oil because of a missing o-ring
(another part we are picking up on Monday). This housing I am refering
to looks like an oval on it's side. The diaphrams in the carbs looked
good. How would idle mixture passages and idle jets affect this
problem? Wouldn't this concern the high speed jets? If the jets were
plugged wouldn't it be highly coincidental that both are plugged up?
Not to be critical, just trying to understand =)!
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph 

FB wrote:
> nomorespameventhoughthejapanesespamgivesmeachuckle wrote:
>
>
>>I think we'll try and clean the filters with some kerosene and petrol.
>>We live in Iowa and I'd hate to have a small piece of dirt or stone
>>from the gravel roads get taken up the air intake and make itself into
>>the engine and ruin a piston. We'll try this Monday night (if we can't
>>get new ones).
>
>
> Methinks you worry too much.
>
> If you are really really really worried about a bit of grit getting to
> the piston, cover the carburetor inlet with some window screen.

FWIW: You seem to be talking to someone from farming country. No filter
is a hard sell to any farmer. I don't think it will ever happen.
 >> Stay informed about: 1969 Honda CL350 Doesn't Go Above 40mph