front fork movement/flexing

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itheo58
Posts: 33
Joined: Fri Sep 19, 2014 11:00 pm
Location: Nowra
Interests: Honda750 Santee,Yamaha RD250. 1928BSA2 stroke

front fork movement/flexing

Post by itheo58 » Thu Nov 12, 2015 1:06 pm

G,day.Is it normal to have any movement in the front forks ? My bike is now getting close to being fully assembled and notice that if I lock front wheel and try and turn left or right under load that front guard was twisting a little. On close examination it seems there must be slight play where top seal is. multiplied by length of front forks. There must be some play otherwise forks would not slide feely I would imagine.
I have yet to remove wheel and check each fork but dont recall beiing loose and sloppy.
Any ideas? as to what would be considered normal.
My mudguard has about 1/2 [12mm ] inch flex to each side at bottom .
Hope my pictures post of my bikes progress.Have yet to have running but engine rebuilder had running in a donor bike.
Have to fit baffles in my pipes and fit an indent or modify side stand but all else is fitting correct cables and hoses.
Thanks Theo.[Ian theobald ]

Prof
Founder, Choppers Australia
Posts: 5954
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
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Re: front fork movement/flexing

Post by Prof » Thu Nov 12, 2015 9:23 pm

CB 750 forks extended 6" flex (twist) without a fork brace. In some cases when putting the forks on full lock, the brake can drag. If your brake is not dragging I wouldn't be too worried, as it not very noticeable when taking off and when riding.

Bike looks really great. When will you get the forwards attached?

Received your email, but wanted to do a bit of thinking before I answered a couple of your questions.
Chopit'nrideit... Prof

itheo58
Posts: 33
Joined: Fri Sep 19, 2014 11:00 pm
Location: Nowra
Interests: Honda750 Santee,Yamaha RD250. 1928BSA2 stroke

Re: front fork movement/flexing

Post by itheo58 » Fri Nov 13, 2015 8:54 am

My forks have a brace half way between bottom triple clamp and top of tube.My forks are 8 inch and were ok with 550 rule when slip 2 inches through top clamp without engine in frame.
Have not measured yet but bike will be on club plates now that this 60 day rego trial so rule may not apply as bike is 1975
Perhaps is normal to have slight flex as never noticed much slop in tubes and guess they have to move
Mudguard can be seen to flex across 1/2 inch at bottom of tyre at reat if lock front wheel and try and turn bars left or right .
Do you think bike needs front pegs? Thanks Ian

Prof
Founder, Choppers Australia
Posts: 5954
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
Contact:

Re: front fork movement/flexing

Post by Prof » Fri Nov 13, 2015 9:39 am

Sorry, didn't see the mids.

You might be able to get your fork brace a bit lower without mudguard hitting it which would help. Only other suggestion is that iff the flex is a bother, that you make up a stronger mudguard mount. I did that on one chopper to reduce flex. Made it out of 6mm thick stainless and ran it over top of guard. Guard was then mounted under the brace instead of on top. Looked fine.

I wouldn't do anything until you've ridden it. If ok don't bother. My son's CB550 is 10.5" over with 45 degree rake and is very floppy when moving lock to lock at a standstill, but you wouldn't know it on the highway and it is fine cornering as well.

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Chopit'nrideit... Prof

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