125cc Sportsbikes Forum banner
1 - 7 of 7 Posts

Registered
Joined
4 Posts
Discussion Starter · #1 ·
So in 2020 i wrote a post asking about fitting a mito conrod into a freccia engine.
Everything was great all the seals gaskets and the rod it self fitted perfectly.
I did the rebuild of the bottom end ,but now I have another problem.
Trough out the year I have spent a LOT of time on this forum reading manuals and so on.
I have found out that my freccia was molested beyond my believe. So ...
Here we go.

It has a 66650E cylinder and not the original 60433 the 66650E was sleeved with the iron sleeve.
The sleve was cut so bad it is not even funny . Ports are terrible not matched at all .Some are
Wasy smaller than the cylinder itself and so on .

Head is presumably the original . It is black and unmarked (so the normal dome top).
The Piston was a prox that had literally more than a 1mm of slap in the bore.
Compression was about 115 psi (about 8 BAR).


So all in all , I need a new Nikasil cylinder, and piston combo .
Was looking to simply buy mitaka cylinder with wossner piston and we are done .
But brain kicked in and I realized the problems:::

I did not measure the squish . So the bike has a 91 mm cylinder with a dome top.
Gasket is probably 0.5 or something similar. I think that squish should be 1.5 or even bigger,because it is an early combination.

So if I buy the mitaka one, that is a copy of 73037 (91.9 mm) . If I use the dome top piston and the original unmarked head , and even if I used the smallest gasket,
I would be wayyyyy of with the squish!!!
About 2mm or more from what i have been seeing. So what is my best choice,
Is there a way to mill the Zylinder ( like skimm the top ) or even bottom ( for it to drop more )
I fo not know what to do . Cant find og 66650e .at all. And when I find them it is too expensive for me.
So in the end the squish is my enemy
Pls If anyone knows the best option or what to do please comment on this post.
Thank you very much 馃挅馃挅馃挅馃挅馃挅馃挅馃挅.



Tire Wheel Plant Motorcycle Automotive lighting
 

125cc Sportsbikes Boffin
Joined
3,178 Posts
Problem with skimming the top of bottom is damaging the plating. Plus you will affect the port timing. Need to figure out what port timing you need (realistically the skim is likely to need to be to the bottom of the barrel for the port timing to still be the same relative to the piston at TDC of an engine built to run a 73037)

All the best

Katy
 

Registered
Joined
2,879 Posts
in Original none sp C12R '89~'91 with:
-5P engine casings,
-60433 91mm (91~91,05mm)
-and Black unmarked Hemi cylinder head
-no manufac variation on the DomeTop piston heights or dome radius.
-with compressed base gasket, (new Thickness varies depending of a manufac: Athena,Centauro, Corteco,Ne-Brand Taiwan) lets say as new 0,55 and as Compressed into 0,45mm thick, the Squish iirc is summink 1,65mm ~ 1,95mm

the squish edge on Factory original ^^ above head itself is 1,35mm iirc.
this piticular cylinder head is the 1 out of couple Cagiva/Gilardoni head's that has huge amount of material in it which allows plenty of Head skimming. i cant remember atm the exact mm amount before water jacket is punctured through but about minus 2,5mm max skimmed. it can be skimmed so much that the Water pipe connection is Flattended a bit...


So best option for you if on Budget and in a difficulty to source spares, is to buy the Mitaka which is 91,7mm height (thats what is used to be at least, i dont have Data from currect product batches, but 91,7 was the case for like 10years...
Very early 1st Gen Mitaka's were little different Vs later ones......and as said current Product Patch unknown to me...

then skimming your Stock cylinder head, including O-ring grooves, which are the most delicate thing on the Skimming prosess.
Actually on early '89 production the O-ring grooves had a Manufacturing tolerance and were not always Symmetrical flat bottomed as supposed to.....but it never caused and Leak issues......

i dont atm remember Mitaka's PortMap measures Vs. 60433 regarding distance from skirt to bottom of Exh , but Mitaka will slightly Prolong your Exh port Timing... Positive result....

and regarding base gasket Manufac brands, the "Ne-Brand Taiwan" ones have best range on the 3 included in the kit: 0,35 0,45 0,55 iirc. Where as OEM Athena has little thicker steps by 0,05mm
That said, Cagiva in past sold a OEM Athena gaskest ranking from 0,1 into 0,9mm. in 0,1mm steps Due because of a Sp Lucky Explorer....

ps. remember to to Match CTS-blade model/profile into chosen cylinder.
Mitaka would use 73037 A0401 Blade, ideally.


i have about 7 Freccia's these days, or maybe more as parts....
 
  • Like
Reactions: Kickstart

Registered
Joined
4 Posts
Discussion Starter · #4 ·
Thank you soo much for all of the replies, i have read a lot of cagiva4ever posts and a lot of mito posts before. So I that is it . Its a bit too late now. I have found a 60433 og brand new replated cylinder and vertex piston . (Propperly mached tolerances) . Bought it for 270Euro. I know it isn't the best deal but the place was close by and a could personally inspect the parts.



I have personally rebuilded the engine

Gearbox bearings clutch bearings and so on was not changed. (small things that ware in good shaoe)

Font Auto part Electric blue Plastic Electronic component


New crankshaft ( con rod) Samarin . The brand was recommended by the online seller because they didnt have the proX one. I was impressed with the quality. It is forged beautifully, top wrist pin part of the rod is sooo thick,all silver plated bearings and copper spacers at the bottom con rod bearing

The crankshaft was pressed by a specialist and was centered also ( naturally ) .
The box looked like this ( the box is not mine it is only an reference that i found online). The picture above is mine.
Light Musical instrument Font Food Rectangle



Next thing war the main bearings : I decided to use SKF (c4) bearings with polymer cage
Automotive tire Camera lens Lens Camera accessory Carbon
Hand Automotive lighting Automotive tire Hood Camera lens


All of the seals war in a kit (set) made dy athena , same deal for the gaskets
Motor vehicle Automotive tire Automotive design Toy Automotive lighting

Audio equipment Gas Font Gadget Circle

all of these parts ware bought in germany , because I live there currently .
I I do not have the ability to back to Croatia (the current location of the motorcycle),
and because of that the rebuild progress was really slow.

So at last , 1 week of free time .
went to croatia as fast as possible and started the rebuild

Feast your eyes on this s*** show
1.
With 1 set of spanners and a set of socket wrenches I and my friends started to dissasamble the engine
(It is surprisingly simple to remove the fairings to disconect everything and to pull the engine out )


Motor vehicle Gas Waste Auto part Machine

Bottle Drinkware Liquid Fluid Glass bottle

Automotive tire Gear Bicycle part Rim Auto part

Bicycle part Personal protective equipment Tool Machine Auto part

there is unfortunatly not enough space to fit all of the stuff on the post so I will continue bellow
 

Registered
Joined
4 Posts
Discussion Starter · #5 ·
So the dissasemly went soothly for the most part (F*** the magnet ).
Also i forgot to post pictures of the cylinder.
There is not much to say . the pictures are saying everything.
I have put the engine together repainted it and put the new bolts and washers in .
(internal engine bolts and bolts that fassen the half cases have been reused . water pump cover clutch and magnet covers are the fassened by new screws)
Wood Audio equipment Kitchen utensil Circle Flooring
Here are the rest of the pictures
Motor vehicle Gas Auto part Machine Automotive exterior

Automotive tire Motor vehicle Rim Bumper Machine

Automotive tire Automotive design Motor vehicle Rim Auto part

Bumper Power tool Auto part Wire Bicycle part

Motor vehicle Gas Machine Auto part Automotive wheel system

Automotive tire Motor vehicle Automotive design Automotive exterior Gas

Electrical wiring Audio equipment Automotive tire Wire Machine

Gas Auto part Metal Rim Machine

Automotive tire Motor vehicle Camera lens Gas Machine
 

Registered
Joined
2,879 Posts
Samarin is 1 of the Best Rod's available.

Prox C-rod is not a Cagiva specific and it weights 30Grams more than OEM rod. its actually very old early Yamaha DTlc rod which has a bottom GudgeonPin swop made to fit Cagiva 5P/N1. its not designed for Cagiva originally....

Congrats for choosing the Best possible parts ! espec including TN9's p66 polymers. they can last upto 35 000~45000km in FP bike setup properly.


to be safe, id ask you:

- Did you take special care to Balancer timings ? (not following wrong W.S.M and typo on it..)
*checked also compressions prings qty:3 in twing spocket assy ? (on later N1 engines they tend to snap-break, but so far never on 5P)

-Did you take special care to the O-ring at Crank at RH-side ?

-did you SetUp "Crank alignment" between engine casings ? commonly on 5P 0,8~0,85mm per side. sometimes arrely 0,9mm
*did you use the commonly 0,5mm thick shim washer between LH-main bearing and Crank ?

-did you check waterpump aluminium impeller Clearence into LH-engine casing ? ( they too often from Cagiva factory assembly, are rubbing against engine casing very badly.....)

-and lastly, when adjusting CTS-blade/piston clearence, also take extra care on the edges/sides of the chamfer at blade where the clearence/gap tends to be too small versus middle area.....
(i have written a long Detailled instructions how to setup the CTS-servo 0-point/reference point etc, which none are told at the books/W.S.M's. article should be still here at forum on very old post/topic...)
Would be utter soreness if scoring the pistons or burning the servo/computer unit if summink missed on Setup...
 
  • Like
Reactions: wertyu-2007
1 - 7 of 7 Posts
Top