Metz. psi recommendation doesn't conform to "my" bike. - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 17 (permalink) Old 10-30-2010, 03:51 PM Thread Starter
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Metz. psi recommendation doesn't conform to "my" bike.

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post #2 of 17 (permalink) Old 10-30-2010, 04:36 PM
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Quote:
Originally Posted by FlacoLove View Post
Relevant Info: (1988 VN750, 31K miles). Two weeks ago, bought, balanced, installed ME880 Marathon's, (I weigh 160lbs), I put 36psi front, 42 rear, and nearly killed myself! Bounced all over the place. Tweaked (cold) a pound or two and still bumpy. After the 100 mile break-in, I put in my "Ride-On" Tire balancer/Sealant (5oz/front, 8oz/rear) and though it got a lil better, I still wasn't confident at high speeds; the bike was not handling. I re-read the post, manuals, Metz's recommendations, BMW's flex theory of 3 pound hot/cold difference, then our verses hit me with very important insight that made sense: My suspension? (I bought my bike with black elect. tape covering my front fork seals; you go figure). My bike seems to handle/grip and feel better with a lower psi at ALL speeds, then the Metz. recommendation. I Presently have 28-29 front, 31 rear (cold). After about 40mins highway speed (hot), they're 34psi rear (perfect), but still only 28 front; which means that the front tire is NOT flexing as it should/suppose to be? But god forbid if I should go below 28psi, right? (Hoss?) I do know that the rear tire now gives me everything I ask for (and some) for all around/all weather performance; top notch! Wow! And the front tire goes over any and everything as if it were all flat road (even paralleled hi/low areas). These are amazing tires but getting the proper psi is still an on-going process because at 60-70mph, the front sort of...bounces? bumps? I do know that the handling is...shaky and I let off the throttle. My old front tire only held 22 psi and was nice to ride (no bumps)! Ride safe..
OK, I`m no tire specialist, I was only passing on the 3 psi difference in cold/hot inflation recommendation that I remembered. But I think you are probably right not to go below 28 psi in the front tire.

I wonder about the black electrical tape wrapped around the fork seals. Are the fork tubes free to slide in and out of the lower section without sticking?
If not, could that be contributing to bumpy, bouncy, shakey front end?

Have you serviced the fork tubes? Do they have the proper level and viscosity of oil installed?
See lances fork rebuild thread:
https://www.vn750.com/forum/showthread.php?t=12827

If your shocks are not set up properly, or if something is broken inside, it is conceivable that a too soft tire could make a stiff suspension feel better to you.
I think your `88 model still had provision for air adjustment/preload in the fork tubes.
Any possibility they are pumped up too hard?

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Last edited by OlHossCanada; 10-30-2010 at 04:44 PM.
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post #3 of 17 (permalink) Old 10-31-2010, 01:08 AM
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Quote:
Originally Posted by FlacoLove View Post
Relevant Info: (1988 VN750, 31K miles). Two weeks ago, bought, balanced, installed ME880 Marathon's, (I weigh 160lbs), I put 36psi front, 42 rear, and nearly killed myself! Bounced all over the place. Tweaked (cold) a pound or two and still bumpy. After the 100 mile break-in, I put in my "Ride-On" Tire balancer/Sealant (5oz/front, 8oz/rear) and though it got a lil better, I still wasn't confident at high speeds; the bike was not handling. I re-read the post, manuals, Metz's recommendations, BMW's flex theory of 3 pound hot/cold difference, then our verses hit me with very important insight that made sense: My suspension? (I bought my bike with black elect. tape covering my front fork seals; you go figure). My bike seems to handle/grip and feel better with a lower psi at ALL speeds, then the Metz. recommendation. I Presently have 28-29 front, 31 rear (cold). After about 40mins highway speed (hot), they're 34psi rear (perfect), but still only 28 front; which means that the front tire is NOT flexing as it should/suppose to be? But god forbid if I should go below 28psi, right? (Hoss?) I do know that the rear tire now gives me everything I ask for (and some) for all around/all weather performance; top notch! Wow! And the front tire goes over any and everything as if it were all flat road (even paralleled hi/low areas). These are amazing tires but getting the proper psi is still an on-going process because at 60-70mph, the front sort of...bounces? bumps? I do know that the handling is...shaky and I let off the throttle. My old front tire only held 22 psi and was nice to ride (no bumps)! Ride safe..
I would say you have some issue here that needs to be addressed ASAP (i.e., bad tire, bad balance, bad suspension, etc.). Metzeler recommends a minimum of 36psi front/40psi (cold tires) rear for stock sizes (need to add psi for heavy riders, luggage, 2 up, etc.). I put OEM size Metzeler ME880 (stock sizes) on in May and weight 155lbs. The bike has stock shocks set to factory settings for a 155lb rider and I run 36-38psi front/40-42psi rear (no difference in performance +/- 2 lbs). I've had no issues that you describe. In fact, the bike has handled more like a sport bike from the first day I installed the Metzelers. I had to restrain myself during the first 100 miles because they were that good.

28 psi on your front Metzeler is too low! That's a good 8psi below the minimum set by the manufacturer. If you can't run at least 36psi without issue, then you have some safety problem with the tire or bike that needs to be addressed.


Chris Glennon - Portland, OR
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post #4 of 17 (permalink) Old 10-31-2010, 03:35 AM Thread Starter
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post #5 of 17 (permalink) Old 10-31-2010, 09:26 AM
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First I will say right off that eveyone I know that installed the Metz reported the pressure they used was in the 36-38 front , and 42-44 rear. Some of these folks have put thousands of miles on their bikes and still rave about the tire...no reports of accellerated wear (a problem with improper tire pressures)

You seem to be trying to solve a problem your bike has by compensating for it somewhere else...meaning you obviously have a major suspension problem and your fix for it is letting more air out of the tires as opposed to repairing the suspension.

It is of course possible that there is a serious ballance problem with the tires you installed, or they may even be defective...

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post #6 of 17 (permalink) Old 11-01-2010, 12:12 AM
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I would vote defective tires but with the ride-on and just the fact that are tires let alone motorcycle tires good luck getting anyone to consider the warranty.


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post #7 of 17 (permalink) Old 11-01-2010, 12:42 AM
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Quote:
Originally Posted by FlacoLove View Post
Wow, please forgive me as I only seek relevance here but according to Metz. http://www.us.metzelermoto.com/web/p...s/default.page these psi's Metz. mentioned are NOT in recommendation for my tires (100/90/19 front & 150/90 15 rear). Note that the tire sizes that these figures apply to are listed below the listing and that "my" tires are not; or perhaps they are in fact listed...but at the very bottom under engine size 500cc to 749cc (31-36psi rear & 24-34psi front)? I do not want to discount Metz's opening statement in mandatory language which states: quote: "Always inflate tires to the correct pressure as indicated in the owner's manual." unquote. whereupon everything else is "suggestions" based on emphasis; a recommendation, as opposed to the "correct" tire pressure. Note that the elec. tape is only covering the dry rotted caps and that I still got decent suspension up there (Kawasaki dealership confirmed when balanced/installed new tires; no leaks either). I remain...still researching... ride safe.
You are looking at the wrong Metzeler specs: Dual Purpose. The Dual Purpose tire is NOT the ME880. The VN750 falls in the "Touring/Cruiser" category. Give Metzeler a call to verify the correct tire pressure if you are still in doubt. Make sure that you tell then you have a Kawasaki VN750 with ME880's 100/90/19 & 150/90/19.

I'm only try to point out that the recommended tire pressure minimums should not make the bike bounce around. It should be smooth as glass. If not, then there is a problem (i.e, bulge in tire, tire out of round, bad balance, bad suspension, whatever).


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post #8 of 17 (permalink) Old 11-01-2010, 09:13 AM
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Flaco,
Chris, KM and others are providing lots of wisdom here. Something is wrong with your bike.
6'3" 190lbs and I'm running ME880's 110/90/19 & 170/90/15 38F / 42R and it hugs the road like a new girlfriend.

BTW: What does "Bounced all over the place" mean....harsh ride or out-of-balance?
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post #9 of 17 (permalink) Old 11-03-2010, 11:16 PM Thread Starter
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post #10 of 17 (permalink) Old 11-04-2010, 12:28 AM
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Quote:
Originally Posted by FlacoLove View Post
What I meant by "bounced all over the place" was that when I had those high psi's, the bike felt all the bumps, holes, pebbles, and the tires reacted to them by bouncing; nothing was absorbed.
Ok, maybe your tire gauge is not calibrated and reading high? Take your gauge to a tire dealer (racing center is better) to have your gauge compared to a Master Calibrated Gauge. Make sure it is a Master Calibrated Gauge!! It will tell you if you gauge is off and by how much. Take a Sharpie and add the +/- PSI to the side of the gauge for future reference.

Either way, I'm not experiencing what your describing. In fact, I've been pushing my VN750 more and more with Metzeler ME880s and having more and more fun, and they beat the Bridgestone OEM's hands down!


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