cold start trouble

[aarm]

Hi All,

Now that the weather is colder, I'm having dickens of a time getting the R65 started.  Once it's warm, it fires right up, but with the choke all the way on I'll get an initial sputter then it'll die.  If I lay on the starter it'll fire up eventually, but I'm a little at a loss.

Let me preface this by saying, I had a shop rebuild the carbs back in April.  They mentioned that they thought the choke may be sticking a little even after the rebuild and I may want to address that.  Along those lines, if I leave the choke on after it's started, it can die as quickly as well.  This was the case in warmer weather as well.  Is this a flooding issue or more likely a lack of fuel issue?

Any thoughts?  

Aaron

[montmil]

Drop the float bowls, Aaron, and check the small fuel reservoir for the enrichener circuit. Identify the reservoir by observing the long brass pick-up tube that resides within.

At the bottom of the well, there is a tiny "jet" that allows fuel from the main float bowl to enter the enrichener reservoir. if the jet is clogged, it's the devil getting a cold engine to light off as no fuel can reach the circuit. Could be on just one carb bowl or both.

Strip a single strand of thin copper wire out of some scrap wire. Use the soft copper to poke through and open up the fual residue clogged jet.

Confirm the return springs for the enrichener lever are, well, doing their return job.

[Barry]

Not sure what year your bike is. I believe choke operation got more progressive on later models. On my 79 the choke is not very sophisticated in operation. Above 12-15 deg C  I need no choke at all. In colder weather I need to use full choke to start the engine but then have to take it back to half choke or even off  almost instantly. No way will the engine run for more than a couple of secs on full choke except perhaps at - 15 deg C.

[Session101]

mine is the same, when its warm starts so easy, but then cold, it starts for like 1 sec then dies, but if i hold down the starter then it wants to start, after about 10 starts and fine tuning the lever on the choke it finally will stay started, i figure its once the carbs warm up a bit or the chamber itself?

[Barry]

Mine normally starts instantly hot or cold. It just won't run on full choke and the choke operation is not progressive it seems to be either full on or almost off. I believe the reason might be that the  earlier carbs have fewer fuel holes in choke disc. If I had a later disc to copy I might be tempted to drill some extra ones.


If I get it wrong which is rare (but it did happen this morning after the bike had not been used for 10 days) then it can be a bit of a of pig to start.

[Matt Chapter]

At the bottom of the well, there is a tiny "jet" that allows fuel from the main float bowl to enter the enrichener reservoir. if the jet is clogged, it's the devil getting a cold engine to light off as no fuel can reach the circuit. Could be on just one carb bowl or both.

Monte, do you have a photo.. or did this never happen?

I've been having a bit of trouble getting the bike to light off, even over the summer when it was Texas (tm) hot, and I suspect it's that or I need a carb synch.  Or both.

[montmil]

At the bottom of the well, there is a tiny "jet" that allows fuel from the main float bowl to enter the enrichener reservoir. if the jet is clogged, it's the devil getting a cold engine to light off as no fuel can reach the circuit. Could be on just one carb bowl or both.

Monte, do you have a photo.. or did this never happen?

I've been having a bit of trouble getting the bike to light off, even over the summer when it was Texas (tm) hot, and I suspect it's that or I need a carb synch.  Or both.

Gots photo. Lemme find it and post.

Matt, You going to be in downtown Luckenbach on Saturday? I'll be wearing my black "LuftKoph" T-shirt. The cat with a Shiner in has hand.

Found it!

[Bob_Roller]

After you go through the carbs and you still have the problem, check the ignition coil .

I had an OEM replacement red and black coil go bad on me, the cold hard starting problem started at 55 F. and got progressively worse with the temps getting colder .

The primary circuit of the coil had .7 ohms, should be 1.5 ohms .

Another possibility, is a dry starter, one where the lubricant has long since dried out .

This results in more battery power going to operate the starter and not enough to get the ignition to fire a good 'healthy' spark, especially the bikes with electronic ignition, this system doesn't work well with battery voltages below the 10 VDC range .

With cooler, or colder overnight lows, alcohol fuel is harder to get vaporized .

This possibly combined with an older battery that is not as good as it used to be .

I don't know if you have too much of a corrosion problem in Portland, but checking the charging /starting cables and wiring for corrosion, etc....., these bikes are approaching 30 ish years old in most cases .

There are a few possibilities, or a combination of factors causing the problem .

I'd get the carbs looked at first and if you still have a problem, then go into the electrical system .

[aarm]

Thanks for all the responses.  I think that the the reservoir "jet" is an easy first check.  Monte, thanks for the pictures that makes it a no brainer.

If not that, battery and coil tests are my next course of action.  Seems like a pretty common thing on these bikes as I remember reading about the clocked float boat jet in the past.

[Barry]

To clarify the symptoms you will get if the jet in Monte's picture is blocked. If the jet is so completely blocked that no fuel can ge into the pipe at all (easily checked by dropping the bowl and looking in the pipe) then choke operation will provide no enrichment at all.

If the jet is partially blocked typically the engine will start on choke and run for several seconds until the "pipe" is empty. Then because the pipe can't refill from the float chamber or can't refill quick enough any additional enrichment will cease and the engine may stall.  To be clear that jet being partially blocked does not prevent the choke working initially it just doesn't last very long.

The function of the jet is to restrict fuel flow to the choke once the pipe has initially been emptied. This is supposed to have the effect of reducing the initial gross starting level of enrichment after a few seconds of running.  

Therefore if the engine runs rough from the instant it fires up I doubt this jet is your problem.

[donbmw]

When I bought my R 90  it was early summer. It ran fine and did all the servicing that you should do for a new to you bike. Come cooler weather it was hard to start just like yours is doing. Found the fuel bowl stopped up. Unstopped the oriffice and everything has been fine since.

Don

[tvrla]

Hi Aaron!

You've gotten some good advice.

I recently worked on an engine with cold starting, and after going through everything else, took a look at the chokes themselves. Turned out the last guy in there didn't know they were 'handed' and got them swapped side to side - left in the right side and vice versa.

So that's always a possibility to check.

[aarm]

Barry thanks for laying out the troubleshooting logic.  More and more it just seems like the choke jet may just be partially blocked.  But I'll know when I get a chance to look.

You all are such a great resource thanks for the help!

[k_enn]

My bike has always been pretty particular about the choke.  In warm weather (70F) and above, it rarely needs any choke.  But below that, it does need some to get started but once started it will not run with the choke on.  

What works for me is the following:  crack open the throttle just a little, hit the start button, and while the starter is turn gradually apply the choke until the engine is running.  Then bring up the revs with the throttle, and take off the choke.  Keep it running at about 1500 rpm by adjusting the throttle as necessary until the engine is warm.  Once warm, it idles fine.

PS, the comments about the starter and coil are good comments.  I ended up replacing both a year ago, and it does start much easier.  

YMMV

[aarm]

Well, today I used the wire technique on both copper stems and the jet vent on the bottom of the bowl.  I also turned the idle screws up a little.  

Started great after even though I didn't see any goo come out,  but it's much warmer today at 60 F.  Not sure if the choke is the issue, but will see on my next cold morning or evening start.  Replacing the coil could be next on my list, but I'll need a multimeter first.

Any recommendations for a good cheap one?  Harbor freight has a bunch but not sure about the 5 dollar one.