Front forks IP2

[Interpol2471]

Hi all, but I am sure Derek may answer this :lol: I have noticed that at 80 mph+ obviously on closed roads :oops: my Interpol front forks feel a bit jittery and can cause the front end to patter, especially on uneven road surfaces. What fork oil do people recommend / tyre pressures etc? Or has anyone else noticed this on their bike or had a problem with front fork damping / handling?

[Interpol2471]

I have checked my tyre pressures and drained and re-filled the front forks with 10 weight oil 250cc. After another run I am still getting the same symtoms of patter or bouncing on the front of the bike making it feel dangerous to be honest. I am going to take the wheels out and have them checked for straightness and balance but other than that has anyone got any ideas? Today the vibration was so bad I could see the fairing shaking on its mounts which is quite scarey :oops:

[kanonkopdrinker]

My IP2 forks are also very stiff ... lighter fork oil seems to have had only a limited beneficial effect. I will be interested to hear what you discover, but a pattering front wheel does seem to suggest a balance problem.DC

[Interpol2471]

Well I am confident that after measuring and checking everything that I could find the only problem maybe the front tyre. The tyre appears to have a high point when the wheel is rotated on the front spindle, I disconnected the brakes and held them out of the way with a bungie strap and then spun the wheel to check balance and run out. The wheel stopped in various places so I am happy that the balance is close enough and also that the wheel run correctly by using a pointer running on the rim of the bead. This is when I noticed that the outside or contact patch area of the tyre appeared to be moving in and out, so after moving my pointer with some yellow tyre chalk stuck on it I re-spun the wheel. Now I have a wheel with about a three inch yellow line on one area of the wheel where obviously the tyre has deformed and now runs untrue. I am now therefore hoping that with a new front tyre my problems will be over. 8) I will let you know this wekend as I am riding to Kempton Park on Sunday.

[dave perry]

Has the bike been stood a while ? Fido used to pogo down the road when I first got it, a check on the balance machine showed them to be well out of round - cured with new rubber. Are you going for Battax 45s ? They seem to suit these bikes well. Good Luck dp

[Interpol2471]

The bike had stood for about three years before I bought it so it all seems to be adding up now :idea: . Can't understand how I had not noticed the patter before though, maybe I am getting faster as the weather improves :oops: As for tyres I am trying the new Pirelli Sport Demons as I had a new fitted to the rear before Christmas to match the Pirelli front which has now got to be changed. :roll: I know the rear is only available in 120/90 V 18 but it has been fine for my riding so I am going to fit the 100/90 V 18 to the front to match. Here's hopefull

[Richard Negus]

Paul,Spinning the wheel in the bike (speedo cable still connected ?) is not really a good check as there is friction in the bearings and seals to take into account - perhaps explaining why it didn't stop in the same place every time.Even if you fit a new tyre yourself, I would have the wheel professionally balanced on a set of rollers - and watch it being done.I haven't ridden an IP2 with Sport Demons so can't comment. However, I echo dp's recommendation for BT45's and further suggest my opinion that Avons are best avoided unless you're a scratcher all the time.R.

[dave perry]

The Avon Road Riders fitted to fido feel very flighty on the road, but as stable as a table round Cadwell's Curves, - so it's not often you are wrong - but right again ! cheers dp

[Richard Negus]

With a compliment like that, it'll be my turn to buy the cream cakes then ? I noticed the same characteristic with Avons on an F1 ; rock-steady at speed but un-nerving to ride at slow / moderate pace.All Bridgestones seem to be neutral at any speed.R.

[Interpol2471]

Thanks all, the wheel is now in my local Motorcycle shop being balanced and checked. I quite liked the feel from the Pirelli's and they appear to warm up and grip well so I guess better the devil you know :mrgreen: Oh and yes Richard I did have the cable removed to try and reduce any friction :arrow: but it was only being done to give me a clue about if it was tyre or wheel to blame, I know it was not a 100% perfect test I just hope it worked :oops:

[Interpol2471]

Well all I appear to have got to the source of the wobbly front wheel I have had the new tyre fitted and balanced and I also loosened the front forks and bounced them a few times to re-align everything. After this I went to Kempton Park at the weekend which is about a 70 mile around trip or so and it travelled along the motorway quite well at traffic speeds. I think the forks are slightly on the stiff side as DC says and you can feel every change in the road surface but I guess this is heightened by the lack of engine vibration so the only thing you feel while riding is the road surface ripples and not any engine buzz to mask the road noise. I may well strip the forks in time to chaeck their condition but I think I have got the handling back to standard but then again I have never ridden another IP2 Cheers PAul

[Derek Nicol]

Hi all, but I am sure Derek may answer this :lol: I have noticed that at 80 mph+ obviously on closed roads :oops: my Interpol front forks feel a bit jittery and can cause the front end to patter, especially on uneven road surfaces. What fork oil do people recommend / tyre pressures etc? Or has anyone else noticed this on their bike or had a problem with front fork damping / handling?

I have the reputation as the forum gobsh*te! Im actually very quiet in person The front forks on my bike are crap on rippled surfaces, no doubt made worse by the reduction in weight over them caused by removal of the barn door fairing. I have never made any attempt to address the problem, i just accept that on some sections of road i have to either slow down or have my eyeballs rattled so violently in my head that i cant see where im going. Technical solution - slow down.

[Interpol2471]

Thanks Derek I think I am there now with the forks and tyres but I did also find that my fairing mounts on the steering yoke had come completely loose thus the reason why the fairing was dancing for me the other day.

[whiffling clara]

Front forks hard, soft, underdamped, overdamped.........It all depends on what you think is good, normal, ordinary........I've ridden numerous IP2's with fairing and without fairing and have never found the forks too hard or stiff at whatever speed up to what, at my age now, I would call ridiculously fast.Remember that these forks are from the late seventies when they were intoduced. If anyone thinks they are no good then try wallowing around on a big Japanese bike from that era.Accept them for what they are and make sure they are in good condition and dont blame the forks for out of balance front tyres and loose fairing mounts.

[Interpol2471]

Crumbs that was a bit In my case yes I did have a hard out of true front tyre I guess from where the bike had been standing and also loose fairing mounts BUT..I also found the lower fork damper rods were twisted and rubbing on the sliders due to the bikes accident had by the previuos owner and they were also wildly over filled with oil. I drained over 450cc from each leg before stripping and rebuliding thus why they felt over damped on braking and uneven surfaces etc. They still have a very slight knock but I undestand this is normal for the type.And as for bike Jap stuff from the 80's I have had GSX1100, Laverda's, Z1100, Z1, GPZ100RX, BMW R100RS, T150V ,vf750sc, vf750fd, CB750F1 etc etc from that era as I am an 80's boy LOL At present I am in my first year of Rotary ownership and so far I have been very happy with it and the NICE people I have met though it.

[whiffling clara]

Hello Interpol 2471.I get the impression that I might have upset you with my last post. Not my intention I assure you and if that is the case then please accept my apologies. Being a bit of an old Codger I dont understand these Smilies faces - does the glowing mean you're angry or embarrassed, and what does "LoL" mean ?The point I was trying too make was that we all have different standards by which we judge a bike and what suits us. The IP2 suspension is certainly firm but I like it. As I said the front forks are from the late 70's - they were top of the range in that era.Sounds like you've got he forks in good condition now - I hope you are happier with their performance.How do you rate the IP2 steering and suspension compared to the bikes you list ?

[Interpol2471]

No problem no offence taken .. LOL means 'laughs out loud' if you see that and the I take as embarrassed I am getting used to that IP2 handling now and it does feel very steady especially compared to the old GS and GSX Suzukis for sure, and as for 16in front wheel Kwaks oh dear!!!!! I think the front fairing takes some getting used to and that lack of engine vibration I still feel as strange but then again my other bikes are 60's Triumphs or a tricked up Yamaha LC I am alot happier with the forks and set up now after all the pain small jobs I found to do but Richard still thinks I may have to be very careful with shimming to get the front knock to almost nothing so at present it will stay and I will be happy to take Dereks advice and slow down instead of falling off.Cheers all.

[dave perry]

Hi you cranky/sensitive/grumpy/loveable lot ! Next time you are ready for some new rubber, you might want to think about Avon Roadriders. As I have reported elsewhere, a mate of mine with much more & varied experience than me - reported that they make Fido (sans fairing) feel like a 250 moto- crosser ! regards dp

[Interpol2471]

I went down to Salisbury today to the annual MAG show and back via Norton Village to take a snap and the bike ran really well I am using Sport demon Pirelli tyres and they appear to handle really well on the bike so far. You can only get a 120/90 V18 tyre for the back not the 120/80 V18 NML recommend but it has not caused me any problems and appears to have plenty of clearance from the rear mudguard. In corners it grips well enough to cause scrtaching sounds so I guess that is pretty good for general road use !!!!The more I ride the bike the more you learn to love it and the better the bike feels, today it started hot or cold, idled beautifully and speed up the A303 in style. I found that the bike sat at 70mph at 5000 rpm and 80mph at approx 5500rpm does that sound about right for normal gearing?Happy days

[Richard Negus]

Hi Paul,70mph at 5000 sounds a bit pessimistic to me.We used to calculate, with a 110/90 Phantom and standard 17 / 43 final drive, that speed was 15.6 mph / 1000 rpm so that 5000 should be somewhere between 75 and 80mph.Do you know what rear sprocket you have ? You may have the optional 44T but that still doesn't account for the apparent low speedo indication, given that speedos usually indicate higher than true.Time for a mile-post time check on the motorway, just to be sure.I hear Gatsos are pretty accurate too - not that I'm suggesting a few points on your licence as an experiment !Follow a newish Mondeo or Vectra (= company car) through various Gatso areas and see what your speedo reads passing the camera. Don't follow anyone wearing a hat though ! R.

[Interpol2471]

I am going to have to recheck that again Richard, maybe 5000rpm was 80mph ish but by the time I had got in drank some tea and sat by the computer things had got a bit hazy !!!Your theory works at 60mph as I know that is 4000rpm so who knows what I am on maybe i was just happy after another run with no wibbles either there or back.

[Richard Negus]

drank some tea .

Cut down on the sugar lumps - you know it's bad for you !R.

[Interpol2471]

I think it's more likely the Red Bush tea

[gripper]

I know this post is a little old but I'm just about to renew the fork oil in my IP2. Flicking through the manual gives some pretty odd oils none of which have a weight grading that I recognise. I seem to recall using silkolene 20wt when I initially fettled the bike. Earlier in this thread Paul says he used 10wt. Anybody got any views on this matter?TVM Dave E

[Interpol2471]

Still using the Motul Fork oil 10w everything still happy here

[Richard Negus]

The IP2 fork is a bit 'European' compared to, say, a Japanese fork action. I've tried oil grades from 5 to 20 and found that SAE10 suits me best. It's often referred to as Medium fork oil.If you haven't done so already, you may find that removing the tubular spacer between fork top nut and spring improves the action if you don't have the fairing fitted.

[gripper]

thanks gents, looks like 10 it is. I removed the spacer and turned up a small spigotted spacer to stop the springs moving around at the top of the stanchion. The parts list shows a spigot on the fork top nut but it does not feature on my nuts!! The top nuts also have a small bleed screw, not sure about the use of this feature.

[johnbirchjar]

Looking in the Owners Manuel for the Classic, there are more choices of fork oil than you can shake a stick at!!(well,14 anyway)allmost like,If it say's "oil" on the tin? I use Motorcycle Fork Oil,with 275 ml in each leg,(the extra 25ml 'cos of the fairing) and it seems to work just fine,J.B.

[gripper]

Why put extra oil in the forks for the fairing? The weight of the fairing is carried by the springs. The springs are damped by the oil. more oil will make no difference to the action of the forks. You may even end up with a hydraulic lock with more oil. not good. You may consider heavier oil to slow the compression (and rebound) of the forks with the weight of the fairing. My IP2 had one inch steel spacers fitted to take account of the police fairing. They weren't even decent spacers just a couple of bits of steel pipe. crap really.

[johnbirchjar]

next time I do a fork oil change I'll revert back to 250 mil and see if there is any change in the handling,(and I'm sure that I put the extra oil in on the advice from Shenstone,when I first fitted the fairing)J.B.