Author Topic: Front end bumby at low speeds..  (Read 510 times)

Offline Reubs

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Front end bumby at low speeds..
« on: September 23, 2018, 08:03:43 AM »
Hi guys I'm experiencing vertical bumpyness on my front end of 77 cb550f2 at low speeds, Could it be the shorty after market front fender ? Don't have the original so went for this, I have Dunlop K70 tires 350 on the front, are they no good? Really just looking for others advice, the bike is fully loaded bags on the rack  with my girl as well. Doing a trip, rode from Toulouse to Girona yesterday. Everything else is smooth. I have tapered bearings kit to fit, All balls  checked spokes, axle clamps, they're not perfect, tiny gap. Will make sure it's at the back will check wheel bearings chain slack and rear swing arm brushes today..appreciate the help. Once sorted plan to continue along the med coast.
Happy riding folks :)

Online SteveW

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Re: Front end bumby at low speeds..
« Reply #1 on: September 23, 2018, 10:30:40 AM »
I just replaced the fork oil in mine, made a huge difference.
1974 CB550 K0
1980 CB650
2000 CBR929RR Fireblade
1966 Lambretta LI150 Series 3
1981 RD350LC
1972 Raleigh Chopper
1974 Raleigh Tomahawk
2011 Henry Hoover

Offline deltarider

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Re: Front end bumby at low speeds..
« Reply #2 on: September 23, 2018, 11:20:48 AM »
Quote
... axle clamps, they're not perfect, tiny gap.
Are you aware there's supposed to be a gap at the rear of the clamps? The axle holders side marked with an arrow or an 'F' (sometimes you will see they're thicker too) goes front side. Tighten the axle holders on the left side (brake side) first and always torque the front nut first. As a result you should have a gap at the rear side. Check: http://forums.sohc4.net/index.php/topic,102388.msg1391690.html#msg1391690  On 'bumpyness', did your front tyre hit something hard? Is it unround due to a long period of standing? Any chance forks are overfilled? 140cc is plenty.
« Last Edit: September 23, 2018, 11:50:10 AM by deltarider »

Offline ka-ja

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Re: Front end bumby at low speeds..
« Reply #3 on: September 23, 2018, 11:57:06 AM »
Does your aftermarket front guard have a built in brace? you may need a fork brace to stop the sliders flexing.
nice bike,nothing in the bank

Offline Reubs

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Re: Front end bumby at low speeds..
« Reply #4 on: September 23, 2018, 01:43:09 PM »
Hi there,
Yes I am aware of the front axle bracket having a front and back, thank you for checking tho, i didn't know about the left side first and so on, thank you for that too. No my gender just has the 4 bolts that mount into the forks. I took it off, going to check over everything give it a run with nothing on, pilian, bags etc. The tyres were just fitted, have ridden in 400 ks so far. Think I will get a mechanic to have a run and second opinion.. should I change steering bearings ?.. I did fill up up forks to 160 as says in the manual. This could be it hey ? Right fork seal has slight leak too. Could this be adding to it. Thanks guys appreciate it hey.  :)

Offline Nurse Julie

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Re: Front end bumby at low speeds..
« Reply #5 on: September 23, 2018, 04:11:22 PM »
160 ml fork oil from completely stripped and rebuilt forks, less if just drained and replaced as there will be residual left in the bottom below the drain plug.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

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Offline sye

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Re: Front end bumby at low speeds..
« Reply #6 on: September 23, 2018, 04:24:55 PM »
If it's ok without a pillion and luggage then the front end is going very light when loaded. This has the effect of magnifying any imperfections in the wheel balance and truing. It could be that the rear shock preload isn't set right or the shock springs are too light making the back end sag.

You need to check the rear shocks are ok and if not replace them if they are past their best. You could also raise the forks through the front yokes by 10mm which places a little more weight over the front and will quicken the steering a little.

Offline Reubs

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Re: Front end bumby at low speeds..
« Reply #7 on: September 23, 2018, 04:45:24 PM »
Wow, that really makes sense and is really appreciative hey. I'm a newy to all this but really interested to learn. Maybe I should re flush and put 140 cc in forks. I did use ATF ?.. as I saw quite a few guys on here have suggested it..  as I I think what was in there before.. slight read tinge will do all this and let you know. Check my rear shocks too! Thanks so much. The open road awaits. Cruising through the N260 yesterday. Just gets me more amped to get her tuned right !! :)

 

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