Planet Minis

MickUK · 10-14-2009, 10:52 AM

I know the heads are almost identical, But ive been told they take a different size cam bearing?

Could anyone confirm this?

If so does anyone know the process of changing the cam bearings, Does it involve heating the bearing?

Im planning on putting a z-40 cam in my lifan BVH .

firepower354 · 10-14-2009, 11:13 AM

Should both have a 32mm small-end bearing vs the 28mm Honda. Bearing isn't on that tight. I usually hang it in the vice, letting the bearing rest on the jaws, and use a slightly smaller drift to tap it out. Socket, often

Tap the other back on, keeping it squared up.

Watch the inner springs for binding, with the Z40.

Only forgot to swap the bearing once, on a Z40 swap. Messy...

MickUK · 10-14-2009, 11:15 AM

Quote:

Originally Posted by firepower354

Should both have a 32mm small-end bearing vs the 28mm Honda. Bearing isn't on that tight. I usually hang it in the vice, letting the bearing rest on the jaws, and use a slightly smaller drift to tap it out. Socket, often

Tap the other back on, keeping it squared up.

Watch the inner springs for binding, with the Z40.

Only forgot to swap the bearing once, on a Z40 swap. Messy...

I was told by Stomp (who sells the Z-40 bearings) that it was not an easy job to switch the bearings but i might aswell give it ago, They have the bearing for sale for £25 for two weeks.

firepower354 · 10-14-2009, 11:16 AM

Can't take the one off the cam that's in the head?

MickUK · 10-14-2009, 11:18 AM

Quote:

Originally Posted by firepower354

Can't take the one off the cam that's in the head?

Sorry what?

Im pretty sure my Lifan 140 has a smaller bearing on the cam sprocket side, Which i need to switch with the z-40s larger bearing.

Z-40s are made for GPX/YX 140s.

firepower354 · 10-14-2009, 11:48 AM

I see. Sounds like you're swapping from an import to Honda type cam. Most heads are machined for both, on the chain side. I thought you meant the small end.

T Bolt USA · 10-14-2009, 12:01 PM

this is the honda type cam that normally fit the lifan 27/23 heads
TBolt USA, LLC » Pit Bike Engine Parts » CAMS » TB 300 RACE HEAD CAM

terry is correct the far end bearings swap out easy

i have the bearing sizes and legnths list in the same section for the 2 other import TB cams as well

Pat Farsole · 10-14-2009, 01:03 PM

Lifan 120 ~ 138 BVH's had the 70 mm Honda type cams in 'em as stock ...

They were machined to take both the 70 mm Honda cams and the long 74 mm china cams ...

Lifan 140's had the 74 mm cam ... I haven't checked a 140 head out yet but from what people say (the mountain included) ... they give the impression that the 140 BVH's aren't machined to take the both cams like the 120 /138 heads are ? ...

IF so , that means that a Z-40 or any Honda type cam won't fit an LF 140 head ? ... Can someone confirm or debunk that ? ...

The bearing swap is easy as Firepower and TBolt say ... Ooracing is just trying to get his cash ... But he should get a chinese sized bearing that is sealed on one side for the small end ... The cam manufacturers put them on there for a very good reason ...

T Bolt USA · 10-14-2009, 01:08 PM

Quote:

Originally Posted by Pat Farsole

Honda type cam won't fit an LF 140 head ? ... Can someone confirm or debunk that ? .

i personally have installed tbwo300 (honda type) in both Lifan 140cc take off heads and heads we acquired loose from china dist

all the measurments of the tb cams that fit china heads are listed on our site
just measure what you have and see what fits

the were some 27/23 heads from zongshen that took the long cams ,,,,

Pat Farsole · 10-14-2009, 01:35 PM

That's what MickUK is trying to find out ... He wants to fit a Z-40 to his Lifan 140 head but he's not 100% sure because a lot of people cause doubt by claiming they (Honda type cams) won't fit Lifan 140 heads ...

He doesn't want to run a 74 mm cam because most cams in that size aren't as big as a Z-40 ... He obviously trusts the reputation of the genuine Z-40 and doesn't want to end up with a lesser cam OR one that won't fit ...

Now here's something I'd like to know for dead sure ... Does anyone know 100% how a TBW0300 compares to a Z-40 for specs ... ie timing , lift , duration , overlap ...

I've got 2 TBW0300's and the 74 mm race cam , and just like MickUK , I don't want to waste my time buying the Z-40 if it's no better than any of those ...

Pat Farsole · 10-14-2009, 02:10 PM

Quote:

Originally Posted by MickUK

Sorry what?

Im pretty sure my Lifan 140 has a smaller bearing on the cam sprocket side, Which i need to switch with the z-40s larger bearing.

Z-40s are made for GPX/YX 140s.

Well what you need to do is remove your stock cam and check to see if your head has a 42 mm bore on the cam sprocket end ... If it hasn't ... the Z-40 won't fit ... You can't swap the big bearings over ... the Honda cams and Z-40 have a 42 mm bearing pressed onto the very end of the cam ie on the sprocket flange ... Whereas the 74 mm cams have the larger end bearing pressed on first ... then the sprocket flange is pressed on next to it , afterwards ...

In a nutshell ... info from the forums leads you to think that Lifan might possibly have used two different types of head castings on their 140's ... and the bad one's were sent to England and Australia ...

Pat Farsole · 10-14-2009, 03:02 PM

Quote:

Originally Posted by loosestools

the z40 has slightly more duration on the intake and most of it is at the beginning and ending of the lobe profile. On a modified 131 with pump gas compression the z40 is good for .8hp over the tb300.i no longer use the tb300.and be forewarned,there are some black painted lifan bvh that need to be machined and a sleeve installed on the sprocket side in order to use a honda style cam

Thanks for the reply ... great info ... If MickUK's engine has the long cam head he might be better off to either buy the better head casting or just buy a TB 30/24 valve head kit and be done with it ...

tblumer · 10-14-2009, 04:28 PM

any tips on swapping valve springs without a spring compressor tool?

Pat Farsole · 10-15-2009, 06:44 AM

Here's some info ...

how to remove valves - Mini Dirt Bikes & Pit Bikes Forum

how to remove valves - Page 2 - Mini Dirt Bikes & Pit Bikes Forum

MickUK · 10-16-2009, 12:17 AM

Thanks for the replys everyone!

I stripped my head down there, Heres what i found.

My current cam is 70mm long, with a 35mm or so bearing on the sprocket side.

There is infact two places which bearings can do, One is 35mm one is 42mm?

So im guessing the 42mm whole is for the 4mm longer cam, As it is 4mm longer than the 37mm whole if you get me?

Does this mean the z-40 will fit with a simple small bear change on the other side?

Pat Farsole · 10-16-2009, 11:07 AM

I checked a stock Lifan 120/138 Honda type cam out of a new Lifan BVH against 4 different Honda type performance cams and found they ALL have a 42 mm bearing on the cam sprocket end and a 28 mm bearing on the other end so a Z-40 should go straight in your head without any problems ... (Check for retainer to guide / valve to piston / valve head to valve head clearances / coil bind / and rocker to retainer clearances) ...

The stock cam is 70.9 mm long from sprocket mounting face to O/S of small end bearing ... and has 42/28 brgs ... There's a hollow dowel pin pressed into the centre of it ... That dowel pin should be removed from the stocker and pressed into an aftermarket cam for the exact same reason why it's in the stocker ... With the dowel fitted , the stock cam measures 73.5 mm in overall length ...

ALL of the race cams I've got (TBW0300 , Daytona , "GPX") are machined specifically for the dowel but don't come supplied with one fitted ... They all have a 28 mm bearing that's sealed on one side ... The seal ensures that the lobes cop full oil volume by limiting oil bleed off ... IF a Z-40 has the sealed 28 mm bearing on the small end ... there's no need to swap or change it over ...

BTW ... Did you find what was causing that bad rattling noise in your engine ? ... And what price are you paying for your Z-40 ? ... DRATV has them cheap at $40 USD ... Rovaza and TB Parts OZ want $180 AUD each ...

MickUK · 10-16-2009, 12:34 PM

The z-40 has a 42/38mm bearings. So im guessing ill have to swap the small end.

Pat Farsole · 10-16-2009, 01:19 PM

^^^ Are you 100% sure on that ? ^^^ 'Sounds like some nig nog has told you the wrong sizes ... A 38 mm O/D ball race with a 15 mm I/D would be a strange lookin' bearing ...

MickUK · 10-16-2009, 07:39 PM

Quote:

Originally Posted by Pat Farsole

^^^ Are you 100% sure on that ? ^^^ 'Sounds like some nig nog has told you the wrong sizes ... A 38 mm O/D ball race with a 15 mm I/D would be a strange lookin' bearing ...

I emailed stomp and asked them the sizes, Although 38mm sounds way to big for a small end bearing.. maybe it was a typo.

10-14-2009, 10:52 AM	#1 (permalink)
MickUK PM Newbie Join Date: Jul 2009 Posts: 60	Do Lifan and GPX BVHs take different cam bearing? I know the heads are almost identical, But ive been told they take a different size cam bearing? Could anyone confirm this? If so does anyone know the process of changing the cam bearings, Does it involve heating the bearing? Im planning on putting a z-40 cam in my lifan BVH .

10-14-2009, 11:13 AM	#2 (permalink)
firepower354 Advertiser Join Date: Oct 2006 Location: Flint MI Posts: 11,005 My Mood:	Re: Do Lifan and GPX BVHs take different cam bearing? Should both have a 32mm small-end bearing vs the 28mm Honda. Bearing isn't on that tight. I usually hang it in the vice, letting the bearing rest on the jaws, and use a slightly smaller drift to tap it out. Socket, often Tap the other back on, keeping it squared up. Watch the inner springs for binding, with the Z40. Only forgot to swap the bearing once, on a Z40 swap. Messy... __________________ If it has my name on it I did it;) FirepowerMinis.com Custom FPM parts and engines. Parts and service for all makes. Honda Trail Bikes parts and accessories. Pitster/Piranha/Thumpstar bikes, parts, engines and accessories.

10-14-2009, 11:16 AM	#4 (permalink)
firepower354 Advertiser Join Date: Oct 2006 Location: Flint MI Posts: 11,005 My Mood:	Re: Do Lifan and GPX BVHs take different cam bearing? Can't take the one off the cam that's in the head? __________________ If it has my name on it I did it;) FirepowerMinis.com Custom FPM parts and engines. Parts and service for all makes. Honda Trail Bikes parts and accessories. Pitster/Piranha/Thumpstar bikes, parts, engines and accessories.

10-14-2009, 11:48 AM	#6 (permalink)
firepower354 Advertiser Join Date: Oct 2006 Location: Flint MI Posts: 11,005 My Mood:	Re: Do Lifan and GPX BVHs take different cam bearing? I see. Sounds like you're swapping from an import to Honda type cam. Most heads are machined for both, on the chain side. I thought you meant the small end. __________________ If it has my name on it I did it;) FirepowerMinis.com Custom FPM parts and engines. Parts and service for all makes. Honda Trail Bikes parts and accessories. Pitster/Piranha/Thumpstar bikes, parts, engines and accessories.

10-14-2009, 12:01 PM	#7 (permalink)
T Bolt USA Advertiser Join Date: Jan 2005 Posts: 4,791 My Mood:	Re: Do Lifan and GPX BVHs take different cam bearing? this is the honda type cam that normally fit the lifan 27/23 heads TBolt USA, LLC » Pit Bike Engine Parts » CAMS » TB 300 RACE HEAD CAM terry is correct the far end bearings swap out easy i have the bearing sizes and legnths list in the same section for the 2 other import TB cams as well __________________ T Bolt USA ALL top Pitbikes ,Engines and Parts for Pitbikes & Minis Website Contact THECRKID@TBOLTUSA.COM or Call 215-630-3554

10-14-2009, 01:03 PM	#8 (permalink)
Pat Farsole 2nd Gear Member Join Date: Nov 2006 Posts: 389	Re: Do Lifan and GPX BVHs take different cam bearing? Lifan 120 ~ 138 BVH's had the 70 mm Honda type cams in 'em as stock ... They were machined to take both the 70 mm Honda cams and the long 74 mm china cams ... Lifan 140's had the 74 mm cam ... I haven't checked a 140 head out yet but from what people say (the mountain included) ... they give the impression that the 140 BVH's aren't machined to take the both cams like the 120 /138 heads are ? ... IF so , that means that a Z-40 or any Honda type cam won't fit an LF 140 head ? ... Can someone confirm or debunk that ? ... The bearing swap is easy as Firepower and TBolt say ... Ooracing is just trying to get his cash ... But he should get a chinese sized bearing that is sealed on one side for the small end ... The cam manufacturers put them on there for a very good reason ...

10-14-2009, 01:35 PM	#10 (permalink)
Pat Farsole 2nd Gear Member Join Date: Nov 2006 Posts: 389	Re: Do Lifan and GPX BVHs take different cam bearing? That's what MickUK is trying to find out ... He wants to fit a Z-40 to his Lifan 140 head but he's not 100% sure because a lot of people cause doubt by claiming they (Honda type cams) won't fit Lifan 140 heads ... He doesn't want to run a 74 mm cam because most cams in that size aren't as big as a Z-40 ... He obviously trusts the reputation of the genuine Z-40 and doesn't want to end up with a lesser cam OR one that won't fit ... Now here's something I'd like to know for dead sure ... Does anyone know 100% how a TBW0300 compares to a Z-40 for specs ... ie timing , lift , duration , overlap ... I've got 2 TBW0300's and the 74 mm race cam , and just like MickUK , I don't want to waste my time buying the Z-40 if it's no better than any of those ...

10-14-2009, 04:28 PM	#13 (permalink)
tblumer PM Newbie Join Date: Mar 2009 Posts: 59 My Mood:	Re: Do Lifan and GPX BVHs take different cam bearing? any tips on swapping valve springs without a spring compressor tool?

10-15-2009, 06:44 AM	#14 (permalink)
Pat Farsole 2nd Gear Member Join Date: Nov 2006 Posts: 389	Re: Do Lifan and GPX BVHs take different cam bearing? Here's some info ... how to remove valves - Mini Dirt Bikes & Pit Bikes Forum how to remove valves - Page 2 - Mini Dirt Bikes & Pit Bikes Forum

10-16-2009, 12:17 AM	#15 (permalink)
MickUK PM Newbie Join Date: Jul 2009 Posts: 60	Re: Do Lifan and GPX BVHs take different cam bearing? Thanks for the replys everyone! I stripped my head down there, Heres what i found. My current cam is 70mm long, with a 35mm or so bearing on the sprocket side. There is infact two places which bearings can do, One is 35mm one is 42mm? So im guessing the 42mm whole is for the 4mm longer cam, As it is 4mm longer than the 37mm whole if you get me? Does this mean the z-40 will fit with a simple small bear change on the other side? Last edited by MickUK; 10-16-2009 at 12:26 AM.

10-16-2009, 11:07 AM	#16 (permalink)
Pat Farsole 2nd Gear Member Join Date: Nov 2006 Posts: 389	Re: Do Lifan and GPX BVHs take different cam bearing? I checked a stock Lifan 120/138 Honda type cam out of a new Lifan BVH against 4 different Honda type performance cams and found they ALL have a 42 mm bearing on the cam sprocket end and a 28 mm bearing on the other end so a Z-40 should go straight in your head without any problems ... (Check for retainer to guide / valve to piston / valve head to valve head clearances / coil bind / and rocker to retainer clearances) ... The stock cam is 70.9 mm long from sprocket mounting face to O/S of small end bearing ... and has 42/28 brgs ... There's a hollow dowel pin pressed into the centre of it ... That dowel pin should be removed from the stocker and pressed into an aftermarket cam for the exact same reason why it's in the stocker ... With the dowel fitted , the stock cam measures 73.5 mm in overall length ... ALL of the race cams I've got (TBW0300 , Daytona , "GPX") are machined specifically for the dowel but don't come supplied with one fitted ... They all have a 28 mm bearing that's sealed on one side ... The seal ensures that the lobes cop full oil volume by limiting oil bleed off ... IF a Z-40 has the sealed 28 mm bearing on the small end ... there's no need to swap or change it over ... BTW ... Did you find what was causing that bad rattling noise in your engine ? ... And what price are you paying for your Z-40 ? ... DRATV has them cheap at $40 USD ... Rovaza and TB Parts OZ want $180 AUD each ... Last edited by Pat Farsole; 10-16-2009 at 11:12 AM.

10-16-2009, 12:34 PM	#17 (permalink)
MickUK PM Newbie Join Date: Jul 2009 Posts: 60	Re: Do Lifan and GPX BVHs take different cam bearing? The z-40 has a 42/38mm bearings. So im guessing ill have to swap the small end.

10-16-2009, 01:19 PM	#18 (permalink)
Pat Farsole 2nd Gear Member Join Date: Nov 2006 Posts: 389	Re: Do Lifan and GPX BVHs take different cam bearing? ^^^ Are you 100% sure on that ? ^^^ 'Sounds like some nig nog has told you the wrong sizes ... A 38 mm O/D ball race with a 15 mm I/D would be a strange lookin' bearing ...

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