Instability on C5

[gashousegorilla]

You guys are making me nervous.  I am 5'10 and 230# (the fat man).  I have not encountered this resonant wobble at any speed, but haven't beat 65mph yet.  Is this on all of em?

  Don't be nervious, I don't think its on all the bikes. At least from what I've read. No one is trying to scare anbody. Just trying to find a solution, for the guys that are having it. If you had the problem Fatman, it's unmistakable and you would know.

[singhg5]

Thanks Cameron, I hope it works, I'm running out of options. Same experience here with my bike, minus the rain grooves. Starting to see a pattern? India, U.S. Italy. Maybe we all need video riding lessons?

Dan, Cameron and BRADEY:

Hope that your bikes get fixed for excessive vibrations and instability at speeds above 60-65 mph.  It is not an issue that should be taken lightly or dismissed with a disdain simply because some riders have not experienced it.  EVERY rider and EVERY bike should be treated as important.  It is quite clear that you just want a solution or a way of communication to the manufacturer through the dealer or via the importer.

Even though some here in US or other countries may buy RE for its charm and its quirks and opt to use a second or third bike for high speeds, but in India this may be the ONLY bike of the owner.  He or She will ride it at 60 to 65 mph on highway.  Secondly, not many riders use RE in US as their main mode of transportation, but in India this may be their only or main mode of travel.  These new UCE C5 bikes are touted as highway capable, so they better be.

[gashousegorilla]

Well put brother sing. When I get this sorted, we are gonna hop on RT 80, 78 or 287, to get to those beutifull country roads ,out west Jersey.

[singhg5]

Well put brother sing. When I get this sorted, we are gonna hop on RT 80, 78 or 287, to get to those beutifull country roads ,out west Jersey.

I look forward to see you and take our bikes on the beautiful back roads of Hunterdon and Somerset counties of New Jersey  .

[qgolden]

Dan, et al.
If I in any way diminished, downplayed or made light of your issues or the documented issues of stability that has been noted by others then I very humbly apologize.  That was not my intention.

I admire your work, enjoy offering suggestions to solving the issue and look forward to you completing your experiments, you have vast more experience at the road handling aspects of of two wheeled vehicles than I will ever have despite my having restored several bikes and riding all kinds of marques for 35 years.

My intention was to make the point that most of us casual non-stress (fair weather and sunny days) riders do not experience the high speed instability that you and a few others have seen. 

I do wholeheartedly agree that based on the number of bikes on this forum and the number of folks complaining of similar issues the statistical sampling is unacceptable.

That being said, I do feel that the issue is just far enough outside of the norm that if it exhibits itself the the first thing to do is to check and recheck the intended factory settings.  IMHO that will cure a measurable percentage of the bikes with  the issue.  Not all of them, certainly not yours.  Also bear in mind that some folks are far more sensitive to such issues.  You are an experienced canyon runner, I am not.  In my world if I were to pick instability at high speed, I would simply back off on the throttle until it subsides..  In your word, you feel it and it bothers you. It's gotta' be fixed.

Also note that there are a lot of new dealers now selling this marque.  I have little confidence that my dealer, (although a great guy to do business with) would be qualified to anticipate such an issue.  I don't know if they really know how to set up an Enfield.  I had the perception that they did not participate in any factory training at the mechanic level.  So how many bikes are exhibiting these symptoms because the inexperienced dealer does not know what to watch out for upon assembly?

Any Case I was attempting to suggest a logical starting point for the OP,  Based on what I perceived from his post he is not as experienced as you are and  I feel that anytime a handling issue raises its head then you need to start with the basics, and that is chassis, tires, bearings etc.  To most folks that should start with a trip to the dealer.

If I offended then I am sorry.

[gashousegorilla]

 Cheers Quinn, all is cool. I took no offence and can appreciate your prospective. I understand and that's whats so frustrating.I look forward to your input. Thanks for the kind words.But please do not put me above anyone else here. I'm am a working class guy,and very proud of it. Like you and many others here, have spent our lives working with our hands.I know more then some,and less then some. That's all. Like it or not we are committed gearheads, problem solvers. Were the guys all the family members say" I bet Dan or Quinn or bob or scott or who ever, can fix that" or "figure that out". I did have a couple of bikes in a magazine which came out last week. Don't give me a big head . I worked long and hard for that.And to be perfectly honest, I don't think all of my family even knows about it yet. Why? Because right now my problem to solve is this bike.I tend to get deeply involved in my projects. I love doing this and can get very passionate.So if I came on too strong, the apologies are mine to offer.
Dan.

[BRADEY]

Thank you all guys for pouring in your thoughts. To begin with I purchased this model of RE only because the company clearly advertised it as a bike you could use for an all day cruise at 70 MPH, which I think its engine is quite capable of.

And I do not agree with people who wish to suggest that a sharp handling bike should not be stable stable on high speeds. Hell even my Vespa scooter with a much shorter wheel base and far more sharper handling is more stable than this bike.

As Singh says, this bike in India is used like a Harley to cruise long distances, and considering that I am sorry to state that RE has failed on two counts with this bike, A) Comfort, B) Instability on high speeds (which is the forte of this model, at least for Indian riding conditions). I suppose they designed it more for the US markets where this would mainly be used as a second vehicle to do trips to buy CHEESE & BREAD, or do a sedated 50 MPH on the CURVING back roads, rather than serious long distance munching (sorry if I have used too many food words here, seems I am hungry  ).

My earlier bike an Iron head 350 in stock condition can do 70 MPH as well. And though it tops there, but she never wobbles even though you are kicking her hard.
I prefer riding it mostly at 50 MPH which she is very capable of doing all day long.

[Rusty]

Also note that there are a lot of new dealers now selling this marque ........... I don't know if they really know how to set up an Enfield.  I had the perception that they did not participate in any factory training at the mechanic level.  So how many bikes are exhibiting these symptoms because the inexperienced dealer does not know what to watch out for upon assembly?

A good point, soon after I bought my bike I asked my dealer about the UK importers training programme, the response was that they hadn't had any training but the bikes are so simple they didn't need any. Well perhaps the C5 with its new frame is sufficiently different to warrant a bit of extra care.

As regards the instability, on my bike it happens at speeds when the engine is feeling a bit stressed so I rarely ride that fast. Those suffering at lower speeds must be struggling.

Things that I will check are the tyre pressures, swing arm bearings, the head race bearings, fork oil level, and all of the engine mounting bolts. I can’t think of anything else that would cause the bike to wobble that I could fix.

[Maturin]

"Things that I will check are the tyre pressures, swing arm bearings, the head race bearings, fork oil level, and all of the engine mounting bolts. I can’t think of anything else that would cause the bike to wobble that I could fix".

[/quote]

..ahem...I can, Rusty 
Check your wheels. Mine were beautifull, no question, but not round. The side clearance was about 3 mm, the height clearance was 1 mm what was close to protest. But since I have a G5, I don´t have much problems with stability.
Another point is the wheels balancing. I don´t think they are balanced in the factory, I never saw any weights on the bikes. I experienced some very strange effects of wrong-balanced wheels in the past.
But my odds on favorite for wobblebuilding is the fork. The C5 fork may be a bit different from the G5´s but they are mounting the same fethers and the same oil (that is probable thin enough to be replaced by one of Singhg´s stronger tea brands). There is a German Company offering improved progressive fethers (http://www.wirth-federn.de/  - time to improve your german, gentlemen  ). Already appointed, not yet delivered, I´ll keep you guys posted.

[ScooterBob]

When I was a dealer, I used to freak out over the "no wheel weights" - I started checking the front wheels before I put them on the bikes - and pulled a few random rear wheels for checking also. I found that they were ALL, without exception, DEAD NUTS perfect. Zero balance and the runout and side to side were well within acceptable for a steel wheel. The India boys can build a damn fine hoop if you ask me!

You are correct, however, in that a wheel imbalance is one of the biggest causes of attaining the frames resonant frequency - and therefore a wobble. The "noise" that I'm getting is that the frequency is about 4 to 6Hz - and that would be about wheel rotation frequency.

[gashousegorilla]

Yea, I also found the same. No weights on mine. pulled the wheels and balanced them, they were off, but not much.Definitely nothing I could feel.An imbalanced wheel would likely start off at speed with a continuesly increasing shudder or vibration.This is not the feeling I'm getting with this issue, It more like the bottom falls out of your stability a high speeds, then stop, then will do it again.With a definite light feel to the front end. Leaving you wondering what the hell was that.It's probably a combination of weight and geometry, both the rider and the bike. That's why guys are feeling it at different speeds, or not at all.

[ScooterBob]

Yea, I also found the same. No weights on mine. pulled the wheels and balanced them, they were off, but not much.Definitely nothing I could feel.An imbalanced wheel would likely start off at speed with a continuesly increasing shudder or vibration.This is not the feeling I'm getting with this issue, It more like the bottom falls out of your stability a high speeds, then stop, then will do it again.With a definite light feel to the front end. Leaving you wondering what the hell was that.It's probably a combination of weight and geometry, both the rider and the bike. That's why guys are feeling it at different speeds, or not at all.

Just wondering, GHG - Have you tried any different rear spring adjustments to load or unload the front end? How's the oil level in the front forks, too? I'm REALLY curious here - YOU are the only one who has, so far, attempted to DEFINE this wobble and tried to quantify it. I cannot, for the life of me, re-create this on the test junk under anywhere NEAR "normal" conditions ..... Sign me "Still Searching"

[CMB]

Didn't mean to scare anybody. I was just relating my experience.

Cameron
(still waiting for CARB approval so I can join the RE club)

[gashousegorilla]

Just wondering, GHG - Have you tried any different rear spring adjustments to load or unload the front end? How's the oil level in the front forks, too? I'm REALLY curious here - YOU are the only one who has, so far, attempted to DEFINE this wobble and tried to quantify it. I cannot, for the life of me, re-create this on the test junk under anywhere NEAR "normal" conditions ..... Sign me "Still Searching"

Yes bob I have. up down and in the middle.I am not with the bike right now, but presently I believe it's set at center. Fork legs are now filled with 20 wt fork oil,(also have tried 10 and 15wt) to the volume in the service manual, again I don't have it with me, but if memory serves me, 200 ml's each? When I drained the stock fork oil , did not measure the volume, but they appeared full, by the amount that came out.
 Not to get off this train of thought, but while I'm thinking of it.My c-5 was one of the earlier ones over here. I believe you guys worked on it, due to the problem with the trans gears. Did not go to recall,you guys picked it up before the bikes went out.Did a good job it appears by all of the fastener paint. Is it possible that these motors have shims, or a motor plate missing or misaligned?Throttle responce is also a factor with this oscillation, or can induce it. And, no I'm not finger tipping the bars on the highway.Just trying to rule all out.
Thanks bob, Dan.

[gashousegorilla]

Here is an interesting link describing motorcycle chassis oscillation. Note that EVERY motorcycle has a resonant chassic frequency!

http://www.vf750fd.com/blurbs/vibmode.html

Excellent read. Gonna need the professor to sort out that Chinese arithmetic though.
So if a duck floats and so does wood, she must be a witch? Sorry I could not help myself. r80rt