Juddering when rolling off throttle on my H2b

[TheHighlander]

I took the H2b that I bought recently, for the first time since I purchased it, out for a decent ride. I bought the bike not seen running as the carbs bowls were full of 2 stroke oil after the bike had been sitting for a year or so. I got the carbs cleaned up, and the bike starts and runs fine other than when you are riding at any speed (not standing still), when you roll off the throttle, the bike has a noticeable judder and clanging sound! Roll back on the throttle and the juddering and clanging disappears. I drained and filled the transmission with 80W-90 Valvoline gear oil before I cleaned and got the bike started ( same transmission oil I run in my other H2’s). Any thoughts? Clutch? It goes into and changes gear reasonably smooth.

[gotz]

It sounds more like a carburettor problem. Sync all carbs very precisely and make sure the air screws are all in the correct setting. Many H2 have this shuddering problem. It is often attributed to worn out needle jets and needles.

[Wolfie]

As Gotz says, the shuddering (more commonly know as surging) is all too common on the H2s making sure the carbs are surgically clean and then balancing them should eliminate it (for a while at least). But the final result can also be helped by making sure that the transmission is all working nicely.

The tension of the chain helps, adjust it so there is 15-20mm up/down available at the mid point, any tighter and you'll be needing a sprocket bearing soon afterwards.
The rear sprocket is rubber mounted (damped) so make sure there is no play there, you shouldn't be able to twist it by hand.
There is also some rubber damping built into the rear plate of the Clutch basket, and again, you shouldn't be able to twist the basket relative to the outer pinion gear.

Your clanging would sort of point to one or other of those damping components having worn, although the surging can be quite traumatic on the gearbox because there is a lot of play anyway. Some bikes will balance nicely and ride lovely, others are absolute pigs simply won't behave no matter what.
Bad surging can absolutely trash what would otherwise be a fantastic ride out, it is sooo annoying. You'll soon get used to the two position throttle, it's on or off.. there's no rolling on or off, 'just trickling it along' doesn't work.

There are other things that can be done to help eliminate Surging. If you have Air filter pods try getting an original air box.
Ivans in the USA does a carb jetting kit with needles, jets etc. People rave about these.
You can fit larger carbs, 34mm will go straight on the inlet manifold but you would need to alter the filter arrangement from standard.
None of the above things are cheap.. It's a H2, unfortunately this is something you'll just have to get used to I'm afraid (and maybe even the surging too).

Good luck.

[TheHighlander]

Many thanks for the replies. When I took the carbs off initially, I really just gave them a cursory clean out and visual inspection, mainly focusing on getting the oil out of the carb bowls. It looks like I’ll need to remove them and go through them thoroughly, and fit new jets. Thankfully I’ve got lots of used NOS parts that I received when I bought my 73 and 75 H2’s, and the airbox will fit from the 75 to the 74 H2b that I’m having the issue with (the H2b has the stock manifold from the car outlets to one large single air filter). At least everything seems pretty easy to get to on the H2’s which is a bonus!

[Nigel S]

Ivans jet kit from the USA will fix that.
I have then in my H1D and H2C. Costly but well, worth the end.

[Wolfie]

Sorry Nigel I'm gonna add the voice of dissent... Ivans might fix it... mine is still a dog I can balance them and get a couple of weeks decent riding before the surging starts to creep back in and eventually it's so bad that I have to clean and balance again.

And I have heard others with the same story, Ivans help but it's not guaranteed,

SInce I balanced them at the weekend I just had a terrific scream along the M62 to work this morning.. as for tomorrow, all bets are off..

[BIG H]

Fitting an Ivan's jet kit to my H2C was a transformation in the way it runs,no more surging & smooth running, worth every penny that the kit costs.
It should be noted that the Ivan's kit was developed using an H2 & not a B or C.
The instructions with the kit are only a guide, you do need to play around with the settings to get the best out of the kit.
Do not blindly follow the instructions when fitting to a H2B/C.

It is also vital that the ignition timing is set properly for best running of your bike.

[malc87]

Need to keep the throttle pinned Rob
Wont happen then!

[TheHighlander]

I’m not sure holding the throttle wide open to overcome my surging problem is going to be a good defense when I get stopped by police HaHa. Looks like I’ll go the Ivan’s route and see how it rides afte that?

Need to keep the throttle pinned Rob
Wont happen then!

[Wolfie]

Keep it pinned in first and you'll barely break the limit..

I didn't even get the full day, I could feel it starting to snatch the transmission on the way home.

[Windy]

I second wolfies "Ivans may cure it". My h2a is different with ivans but not cured. I suspect a worn carb/slide making the setup of the carbs less straight forward and any carberation changes are simply offsetting the real problem (whatever it is!).

A tight chain/ and especially tight cush drive does help.

[Neil the Don]

Best just keep it nailed. Full on, Full off. Ride it like ya stole it, etc .

Juddering ? What juddering !!

[Cliffyboy]

You think these surge they're not half as bad as my gt750 Suzuki I'm lucky enough to have both Suzuki much worse....also nowhere near as fast

[Wolfie]

I thought the Suzuki's didn't have this problem.

Many years ago there were suggestions about trying their CV Carbs on a Kwak Triple.

[Cliffyboy]

Suzuki is really bad mate all my mates that have them complain about it..I've had anti surge jets fitted makes a lil bit of difference ...chain adjustment makes hell of a difference....don't make the I'm gonna blow up anyminuite sound that the h2 does though...don't remember my h2c back in the day making the same noises or bucking about as much...but I only rode it flat out every where ....front tyres lasted well though .

[Barrie]

Have you checked the clutch cush rubbers?

[TheHighlander]

Not yet. I’ve also decided for the time being, I’m letting Seaba Motorcycle Museum out on Route 66 in Oklahoma have the bike to put on display as they don’t have any Kawasaki Triples. I’m busy doing a restoration on a 75 Z1 right now which is taking most of my spare time. Added to this, I just ordered a set of TNT Denco’s for my 72 H2, so I’m going to focus on those two bikes, and get back to the 74b next year. I am going to buy the Ivans jet kit to see how that they perform on the 72 after I change the exhausts and install pod filters. The 72 shows very mild surging at the moment.

Have you checked the clutch cush rubbers?